Hello! Thanks for visiting us here at the Disney Parks Moms Panel.
I think a great Walt Disney World Resort hotel for you would be
Disney's Art of Animation Resort. It is considered to be a value resort and sleeps up to 6 people in the family suits! The resort is themed around Fining Nemo, The Lion King, Cars and The Little Mermaid. Kids and adults love the resort and have such a great time staying there. The family suits include 1 bedroom with a queen size bed, 1 double size convertible TableBed, 1 double sized sleeper sofa, living room, 2 bathrooms and 1 kitchenette. The resort also features the largest resort pool at a Walt Disney World Resort. The pool is so neat, while swimming be sure to stick your head underwater. You can hear Nemo and friends having some fun splashing around! Disney's Art of Animation Resort also have a great food court, Landscape of Flavors, that serves breakfast, lunch and dinner. Transportation to and from the Disney Theme Parks are also included with your resort stay.
As for if it would be cheaper for you all to drive or fly, that is hard to say. For my family, it's cheaper to drive but that is because we only live 8 hours away. Driving from Wisconsin would take considerably much more time than that. Traveling with small children, there are always numerous stops, which adds to the time as well as probably stopping for a hotel room to sleep. I would absolutely keep an eye on websites that have flight deals, like expedia.com, because I think flying would be your best bet.
I hope this helps point you in the right direction. If I can help you with anything else, please let me know. Happy planning!