Wow Cathy, that is a question with more answers than you might imagine! To begin, there is a
page listing all options for parties of 5 or more. It lists Deluxe Villas, Wilderness Cabins, and Value Resort Family suites. All are great options, and cover a range of budgets.
What they forgot to mention was that most standard Deluxe hotel rooms are ones that sleep 5. There are a few exceptions (like the Animal Kingdom Lodge and Wilderness Lodge where the standard rooms only sleep 4), but for the most part these are a great option for you as well.
What do I think is best? I would say the Deluxe villas. While more expensive, the give you more space. But all are good choices, so let your budget be your guide.
If you send me a follow up question (select me from my profile page), I would be glad to give more specific recommendations within any of these categories!