Well, part of the Island Hopping strategy had to deal with the fact that many the islands weren't lone chunks of land, but archipelago chains (Hawaii, the Philipines, Indonesia, Japan are all islands nations/states that include more than one Island... and were also part of the Pacific Theater). So many battles for one piece of territory were spread over multiple Islands... Perhaps use this to make your story... You're not invading a single enemy planet, but an enemy stellar system of planets. This allows for greater diversity. If we look at our own solar system we have the following areas:
Your shore waters would be your Kuiper Belt and Dwarf Planets/Plutoian celestial bodies... Here is where you should consider prepping your fleet for "landing" and taking interior planets. The defender would also likely station patrols and early warning systems here, so at this stage, both the defenses and offenses are have their red alerts and battle stations calls sounded and are mobilizing for battle.
Heading interior, our Gas giants would be our shore (Jupiter, Saturn, Uranus, Neptune). Each of theses are large planets with stormy atmospheres that would hide all manner of fun space station defenses and fleet depots to take. Additionally, all of those planets have multiple moons and plantary rings that can have some fun counter invasion measures. Your radar stations, fuel, scrambled star fighters, gun boats, and other defenses.
Our Asteroid Belt would be the demarkation of the forest line or other change from beach to interior land, and finally the rocky planets and the star (Sun, Mercury, Venus, Earth, Mars) would be the interior of an island. This isn't unheard of as anyone defending a planet in intersteller war will likely have resources spread out into the solar system to stop the advancing ships.... your big ships aren't just the fleet, but the tanks in this scenario.
YOu can see models like this in fiction like Star Trek, where the Solar system does have multiple facilities on other planets that all count to the defense of the Solar system. Headquarters is on Earth, but repair facilities are on Mars, with Jupiter serving as a command center for system movement, coordinating early warning, clearances to enter and leave Earth, and having an air field that can launch patrol fighter shuttles and other equipment. Each of these have ground and space based stations that also have roles to play. While the canon was that Earth was to well defended for a surprise strike, in the show the Dominion pulled it off for a moral victory in DS9 and in Star Trek Online, one of the Klingon missions has you lead a raid on military facilities that end up in a Pearl Harbor like action (basically you blow up ship yards on Mars, crippling repair facilities).
Now, how do we organize this invasion. All ships in a fleet are organized into "Groups". A command structure from the top would be a high ranking Admiral in charge of both the Fleet and lower ranking Admirals in charge of a single group...
What required ships for a group largely depends on your group organization theory and your mission needs... typically, the Group will be the Capital Ship and it's screen ships. Your Capital ship is your big offensive weapon and your screen protects the capital ship so it doesn't have to play defense. World War II is unique in that two different schools of capital ship theory were in different points of their life span: Battleship Theory was on it's way to being phased out, while Carrier Theory was the young hot newness of Naval Combat. Which ever theory you want to go with, keep in mind that the Capital Ship is the offensive ship, and the other ships are making sure that it doesn't die.
In real naval combat, Carrier theory is far superior as it's weapons systems (the planes) are able to better target enemies and from a father range. The Battle of Midway, which was the first true carrier to carrier naval battle, was fought without either side's ship coming within visual range of each other and was fought mostly this way because the U.S. Battle Ships were still recovering from Pearl Harbor and the Japanese developed Carriers to get around crippling restrictions on Battleships that had been placed on it (treaties on Capital ship limitations at the time were written when Carriers were first being tested as a concept at all). Battleship theory has a shorter range but was still used for support of landing forces and while it wasn't accurate, they didn't need to be... those shells still could reach targets out of line of sight and didn't need to hit directly... close was good enough to work.
In Sci-Fi a good Carrier vs. Battleship demonstration is to look at how Star Wars and Star Trek fight ship to ship in space battles. Star Wars uses Carrier Theory as the Star Destroyers (and their prequel sister classes more so) would deploy small fighters and smaller ships that couldn't be targeted by the big guns to fly close and shoot ships. Return of the Jedi has a great "group" mechanic employed where the Capital Ship (Death Star II) has a protective screen of Cruisers (Super Star Destroyers) and Destroyers (Star Destroyers) as well as fighter aircraft (TIE fighters) all engaging the enemy fleet... to the point that for much of the battle, the Death Star II was largely not focused on the battle and it's weapons were actually pretty spot on for its role. As a Carrier, it was much more sucessful as the fighters can be used for offense or defense, while as a Destroyer, the Planet-Blow-Up-Ray was largely scary but ineffective at close ranges. Star Trek is noted for it's lack of carrier ships on screen with the Enterprise almost always being a ship akin to a Battleship (and occasionally submarines, given the nature of both being boats surrounded by hostile environment). Almost any ship to ship engagement is sure to be broadsides with lasers, which suits battleship theory, and the shuttle compliments are never used in engagements. Deep Space 9, which shows fleet actions actually uprooted it completely by using organizations that would be based off of air-force operations, not naval operations (Sisko would repeated call out to "wings" instead of "groups" in the multiship battles).
A typical Carrier "Group" (which in the modern world, is enough) is usually alone and rarely works in a fleet. The United States is the only nation at time of writing with more than 2 carriers... 11 to be exact... and that's only counting the 11 Nimitz and Ford class super-carriers... the American Class "Amphibious Assault" ships aren't "Carriers" in U.S. Navy terms, even though they are bigger than most non-U.S. carriers and allow for air craft to take off and land from them... which is all you need for carriers to be counted as such... The U.S. has 20 of these). Typically the command of the group will be under a Rear Admiral Lower Half. On the carrier, there would be two people of Captain Rank running the shows. The Captain, who is incharge of the ship's operations and the CAG (never addressed as Captain while Underway... Ships have one Captain... his proper rank is Captain though) who is in charge of the ship's Air Wing (in the Navy, a Wing of airplanes is considered a "ship" for the purposes of Command). The Rear Admiral is also in charge of the Groups Cruiser Captains (Usually two, but numbers may differ for mission), the Destroyer Group Captain (all destroyers have a single Captain in charge, but if he or she is on another ship, the CO on your ship is usually a Commander) and the submarine commanders (Submarines usually have a CO of Commander Rank... they also are not ships, but boats... don't ask me why but never call a ship a boat or a boat a ship... it's insulting, for reasons...). If there are two "groups" in a single battle, typically the Admiral might be higher rank (Rear Admiral Upper Half or Vice Admiral) but will be dual hatted with both Group commander and fleet commander... this is because while any capital ships will have space for the Admiral's staff to due their job, they don't have duplicate space. In a carrier's "Island" there are three general levels for each CO onboard. Captain has the Bridge, CAG has the tower control, and Admiral has a level for general coordination between all ships. Battle ships similarly have a bridge and CIC (in the interior of the ship) to handle communications and multi-ship coordination. Also there is a difference between a Capital Ship and a Flag Ship. A Capital Ship is typically the ship with the most firepower while the Flag Ship is the ship with the Admiral on it (Admirals have individual flags that they are authorized to fly on their ship, hence the name. In the Days of Semaphore, this was needed so Captains could readily identify which ship was giving orders). So if the Admiral decides to run his show out of a Cruiser's CIC, then the Cruiser is the Flag Ship, but the Carrier is the Capital Ship.
In space combat, Battleship theory is a bit more viable if you're going to try for realistic, as the guns in space can have the same range as fighers without having the worry of pilots... And actually, a good portrayal would be using Submarine warfare if you go that route as subs rarely engage targets with a visual contact. On scree, this is boring unless you use the silent hunting for drama (Wrath of Khan does this wonderfully, as does the TOS episode with the first appearance of the Romulans). DS9 often used the Defiant's stripped down and limited space status (and cloaking device) to do sub stories in Space. This also works as Subs fight in 3D spaces as a space ship would, where as surface ships fight on a 2D plane (Wrath of Khan also uses this to allow Kirk to get the upper hand on Khan, who is a brilliant commander from his grasp of surface naval warfare... he doesn't think of space as 3D).
Other options are to make a capital ship a Battlestar (from the series of Battlestar Galactica, the titualar ships are Hybrid Carrier/Battleships. These don't work in navies but the contained flight deck of many space carriers means all the guns of a battleship be viable. Carriers don't have many guns as they can't be fired while in launch or recovery of aircraft... which is kinda the point of making a carrier anyway). Typically space carriers will have the flight deck embedded into the belly of the ship, either running stern to bow or port to starboard or off to the sides like wings. Each have an advantage over the real carrier as Launch and Recovery can happen simultaneously. In the latter two options, multiple runways exist, and one is dedicated to take off and one to landing. In the former, the flight deck is so long, it can do both.
As for ground landings, there isn't a lot as most scifi send woefully underwelming man power to planetary invasions... something akin to Helicopter Transport of Marines from ship to shore is generally depicted (consider those really cool looking landing craft in the Clone Wars finale). Star Trek rarely dealt with on screen ground depictions, though they did say they happened. Part of the reason is the book Starship: Trooper is such a big scifi staple that it tends to be dominant for overall planet wide theaters and it's difficult to show a planet wide scope of ground battle. Starship: Troopers is told from a Marine ground combatant and the military employs power armor for it's infantry. The book does describe that a single individual infantry man can typically cover a staggering amount of terrain by himself... at one point the hero notes that a unit formation with individuals spaced a kilometer apart is a very unusually tight formation that presents a threat of friendly fire from being clustered so close.