If I had the room, I would love to build a whole city.
It is certainly tempting, and I do have a lot of "in-the-box" sets which could fill up a town (Modulars, Police Station, Airport, train station, bank, uhhh Space Center, etc), but I don't think I'm ready to take over the dining room table yet.
City sets I want from LEGO:
- a new service station (last one was 2007, and the new 2012 Parking Garage is disappointing)
- a better harbour set than the one from 2011 (more like the 2007 one)
- another City Corner a bit more advanced than set 7641
- shopping center, museum, zoo, convenience store, a proper hospital, etc, etc