Near a planet.
A planet's orbital path will provide a clean bit of space, a star for energy, a way for people to reference the location, and other minor benefits. Put your city in very high orbit around a planet. In the plane of the solar system and in the direction of planetary rotation will work well (may as well be going the same direction as most of the mass, smaller relative velocity). You'll get minor gravity well and all the benefits.
Planets, by definition, clear their orbital paths of debris. If you don't want to be bombarded constantly with large solar system debris, a planet's orbital path is a good place to start.
Being in a star system will provide energy for your city. Most species develop in star systems , so a star system is somewhere they can feel at home. You get free diurnal cycling if you rotate your city. Besides, what's life without a sunrise?
If you have a city in space then presumably the navigational equipment of visitors is good enough to determine how to get to any coordinates by looking at the stars and a watch. A human won't be pointing their ship at the second star to the right and cruising at warp two until dawn, the most complicated navigation they will have to do is to your web page to look up the coordinates of the city. The computer will do the rest. So, being in a star system near a planet doesn't matter one bit for interstellar navigation, but being able to say "Oh, this place has the best Korblian Ale, it's around Howsian-4" gives the place a natural language reference. If your city is called New Portland, it will be hard to find unless you've got a planet and star system (State and Country) to reference it by. Space is a big place, and Portland is an awesome place, obviously there will be a lot of New Portlands out there. Oh, the New Portland around the fourth planet of Howsian? Yeah, I know where that is.
If the planet you're orbiting is an uninhabitable gas giant, then great! No one will ever live there! Guess where that radioactive-toilet-water is going? If it's habitable/near-habitable then it can be used as a rendezvous in an emergency or the city grows into a space port (a high class one, where droids are allowed).
It's something to look at. Space cities should be beautiful, put it above the rings of a Saturn like planet you will make a killing on the real estate.
You can build your city in a captured asteroid. Free solid ground, cosmic ray protection, minor gravity, and micrometeor defence? Yes, please. Minor gravity alone is enough there, make it a health spa, come here and you'll literally weight 10% of your original weight!
So, yes, around a planet.