Well, I would also throw out the idea of a studio villa. I hear they are REALLY small, and why make your kids sleep on a pull out sofa if they can have a real bed elsewhere for the same money or less?
First, I would figure out where you intend to spend the most amount of time (Magic Kingdom, Epcot, MGM, Animal Kingdom). Then, choose a resort that is close to the main park of your choosing.
With your family size, you are not limited very much. Families of 4 can stay pretty much wherever they want.
I will say, though, as a first timer, try to stay in either a MK or Epcot deluxe for the proximity to at least ONE major theme park. It may take you awhile to "figure out" the bus transportation to your advantage, and you will no doubt waste much time on buses if you choose a moderate or value (this has been my experience over MANY trips!)
Of the MK resorts, I would suggest the Polynesian or Wilderness Lodge. Of the Epcot Resorts, I'd suggest the Yacht Club.
I'd stay away from the Animal Kingdom Lodge on this trip. It is a bus transportation only resort, and is really far removed from the rest of the parks besides Animal Kingdom.
My recommendation would lean toward the Yacht Club. It has a fantastic pool, spa, beautiful rooms/lobby, a marina, bike rentals, workout room, ALL the Boardwalk dining/nightlife, plus the Swan/Dolphin hotel within walking distance for MORE dining options. You can walk to Epcot in about 10 min, MGM in about 20 (or take a boat to either). It is luxurious without being overly stuffy and it's located pretty much in the dead center of the WDW property (geographically speaking). It is not too far from anything else. Plus, it is a wee bit cheaper than the MK resorts.
Check on availability and I would rank them in this order:
1. Yacht Club
2. Polynesian
3. Wilderness Lodge (reserve a bunk bed room if they are available)