Hi Alissa!
Welcome BACK to the Disney Parks Moms Panel! How fun that you'll be getting the cousins together by visiting Walt Disney World Resort with your sister! I bet your crew is going to plan some epic matching shirts and jammies. While
The Cabins and Disney's Fort Wilderness Resort and a family suite at
Disney's All-Star Music will both accommodate your Mouseketeers with plenty of space, definitely think of your travel needs as two moms with four kids before you make your final decision.
The Cabins include a bunk bed in the bedroom where the queen-size bed is, which might work out best for keeping an eye on the youngest two. The cabins also have a full kitchen so you can store any full-size groceries and make a child-approved meal if need be. The pool at Disney's Fort Wilderness Resort has a slide, and there are so many great activities here, including a
campfire sing-a-long with Chip 'n' Dale. You will need to take an inner-resort bus to get from the loop of where your cabin is to the front of this resort hotel, which is where you'll then catch a Disney Transportation Bus to Disney's Theme Parks, Water Parks and Disney Springs.
Disney's All-Star Music is within close walking distance of Disney's All-Star Sports and Disney's All-Star Movies, so you could explore their theming and dining locations with ease. (You can also use their resort transportation buses if yours is ever full.) The pull out beds are all in one room, which would be fun for the cousins and provide a bit of respite for you and your sister. This is also popular resort hotel for high school groups.
I hope this helped, Alissa, and We'll See You Real Soon!
~Kristen