Jodim,
I think a lot will depend on what you are looking for in your vacation experience. Heres my two cents. My DD and I have stayed at SpringHill Suites (LBV area) (2006) and thought it was terrific. The location is very close to WDW. The offer free breakfast, the room (Jr. suite type) came with a mini food prep area (mini frig, microwave and sink) and we were close to neighborhood restaurants and the outlets. The hotel does off transportation to/from the parks. I think it would be best to have your own. I am not sure if they have 2 bedroom suites and if they do not you would need at least two rooms to accommodate your group.
The next trip involved three of us (me, DD[10] and younger cousin [14]) and we did some hotel hopping this time around. Initially started off at the Hampton Inn (8150 Palm Parkway, Orlando). All I can say is that I will not go back there again. It was a one night affair until our room at the DoubleTree DTD (2305 Hotel Plaza Boulevard, Lake Buena Vista) was ready. I would definitely do this one again. Rooms were very spacious, breakfast was included in the price I paid and we used the DTD bus service (free for DTD hotel guests) to get back and forth to the parks on most days. The final leg of the trip was spent on-site at Caribbean Beach. As maxiemom indicated, my girls loved the Doubletree much more than the onsite stay.
The last trip (just DD and me) we stayed at the Windsor Palms resort (Kissimmee, FL). Initially, I had a hard time locating the property. But once found it was beautiful. We rented a three bedroom condo, enjoyed the club house, pool, movies, etc. We went to the grocery store and loaded up on breakfast foods, a few quick dinner items, water, dish and laundry detergent and snack foods. I believe most units come with cooking utensils, washer/dryer and dishwasher. We did not have made service so we had to tidy up behind ourselves, which is not awful I just do not like to do it on vacation. The only other downside I noted was the drive to/from the parks. Although, other posters have told me that you do not have to drive up I-4 to get to the parks. Obviously, I still have some learning to do in that area. Windsor has all types of housing and the rates are comparable to area hotels. You just gain a lot more space and after being together allllll day, it was really nice to come back and DD could go in one direction and I could go another. Overall, this was a very good experience.
My family is small in number compared to yours but hopefully some of this information can help in the decision process.