For real togetherness, there are always the Grand Villas in the BWV, with three bedrooms, three baths, a full kitchen and laundry and nearly 2200 sq ft (plus a queen-size pull out couch in the living room. Plus all the grand villas have BW views, great for ppl watching, relaxing and looking over the lake at the BC/YC, viewing the Epcot fireworks. BWV have a great theme pool too, and as you know are walking or quick boat ride distance from Epcot and MGM. They will run you about $1300 a night in peak season, or 1100 in shoulder season, and an even better deal if you have DVC points to use instead (you could try and rent one on the DVC Rent/Trade board), but so worth it for "WOW" factor. (we're thinking of one for February '06)
I would agree that the Epcot resorts will likely suit you party best. A party of about 10 will fit nicely in the GV, and you could get studios or 2BR villas for the rest of the folks, and use the GV as a meeting place.
Have fun planning!