Grandparents have different levels of health/abilities. If stairs are an issue, I would not consider Treehouse Villas. They are great for your group as far as the interior, but I know for my mom that would be a hard no. I guess also consider how important it is for everyone to be in the same room vs. getting 2 rooms, and whether it might make sense to rent a condo-type place (either on or off-site) that would allow you to cook meals, have a living room in which to hang out, etc. Which park/parks do you plan to visit? If your priority is Magic Kingdom, I would say that the Contemporary or Grand Floridian (either 2 rooms or a condo/villa) are most convenient, but from a budget perspective those might not be possible. If Epcot and/or Hollywood Studios are where you will spend more of your time then Beach Club/Yacht Club/Boardwalk/Dolphin/Swan should be considered - either 2 rooms or condo/villas. People seem to like Animal Kingdom Lodge and its villas, and it is nice inside, but personally I find that resort to be too isolated to be a good choice. I agree with a previous poster that the Port Orleans resorts are beautiful and allow boat access to Disney Springs if that is where you want to go; there you would probably need to get 2 rooms. Old Key West also has boat service to Disney Springs, and they have villas there that might be a nice size to accommodate your group if you want to be all in one room. If you will have a car and staying offsite is an option, there are a lot of great condos in the area where you can get 3 bedrooms (and 2-3 bathrooms) which would be desirable for your group, and likely a LOT less money. I guess you have to decide how important it is to be onsite and all in one room, what your budget is like, and also which time of year you are going. If it is a holiday time everything will be much more expensive. Good luck in your choice, and hope you have a great trip!