If you assume you will be detected anyway, hiding is pointless. Indeed counter-productive since it makes you and your intentions seem suspicious and thus effective countermeasures more likely.
Instead you should land your fleet as close to Beijing as you can without causing significant collateral damage during landing and base construction. No reason to be inconsiderate. It is probably better to use five or six locations surrounding the city as that causes less interruption and makes nuclear counter-attacks less practical. The fallout will contaminate Beijing regardless of wind direction.
Simply inform the Chinese that you have come on a diplomatic mission to connect Earth to the interstellar political and economic community. (Annex humanity to your empire. That is the goal, right?) And that you chose the location since Beijing is the capital of the most significant native government and as such makes the best location for the process. (Butter them up.) Apologize for the inconvenience and offer to pay for the use of their territory and extra-territorial status needed for the proper diplomatic status with a technology transfer process and preferred trade status. (Bribe them.)
Note that since you have the technology to make large areas secure from nuclear and aerial attacks, you can protect all their cities from such high tech threats if they are willing to provide the manpower to protect your enclaves against low-tech threats such curious ufologists or American spies. This could be formalized as a mutual defense treaty or if they feel there is a need as a full military and political alliance. Which would make China the most powerful Human power by a large margin. (Get yourself a nice client-state that can provide the slave management services in bulk!)
After you are secure, you can admit that there is no real need to negotiate with more than Human government when you can simply make all the Human nations subject to the entirely reasonable and adequate government you already have good relationship with. I really doubt the Chinese would object to a worldwide Chinese empire, especially if it was gained by the demonstrated technological superiority of your forces instead of fighting of the Chinese soldiers.
Expanded explanation of the rationale for picking the Chinese, can skip
For the political approach the choice should almost certainly be Beijing. It combines the second best economic and diplomatic power base in the World with a political situation and cultural values where they'd have no real reason not to side with you as long as you treat them with respect and generosity.
The US has even better power base, but comes with a complex network of pre-existing commitments, relationships, and attitudes incompatible with being your primary ally and first landing spot. You also wouldn't be able to bribe them by lifting them to the status of most important nation since they already think they are. The Chinese also think they are, but feel that they are being denied proper recognition and would totally love alien confirmation of their superior status.
The Russians also have resentment of the lack of proper recognition of the status they think they deserve and the politics are favourable, so they could be turned IMHO. But their power base is at the moment weak and already committed to ongoing conflicts of no value to invaders. Note that Russians are not really weak, much of their current power just happens to be in form of military hardware and technology the arrival of advanced aliens would instantly render obsolete.
Alternate approach not using the Chinese that might work
One alternate landing spot that might work would be Mecca. Anyone trying to nuke Mecca without you providing a very strong reason why it absolutely must be done would trigger... letting the aliens get settled would probably be seen as the better option unless you flat out declare your intent to conquer the planet.
Additionally, if you inform that you have heard of Islam, feel it is the truth, and have have come to learn more and commit pilgrimage as required of Muslims capable of it, the local governments would actually pretty much have to give you the benefit of the doubt. There would be a valid (I think, not theologian) argument that you are demons, just pretending to be Muslim converts, but it would be very difficult to make that decision fast enough to prevent you from digging in.
And if you could actually convince people that you are really Muslims and are here for religious reasons, it would make annexing and assimilating the planet much easier. Islam already provides a model uniting the entire humanity under a single Islamic state you could use. Given your technological superiority and a consistent strategy, it might even be relatively peaceful. Islam really does have universal appeal even if the current forms tend to be too conservative and dogmatic to really show it off.