Some repeats...we have 5 and have stayed at Polynesian, Contemporary, and Old Key West
The following can fit your family!
Art of Animation Family Suites (Value)
Fort Wilderness Cabins (Moderate)
Port Orleans Resort (Moderate-but the 'fifth' bed is not fit for anyone over 5')
Contemporary (Deluxe)..larger rooms and larger day bed
Polynesian (Deluxe)..larger rooms and larger day bed
Grand Floridian (Deluxe)
Boardwalk Inn (Deluxe) shorter daybed fine for anyone under 6'
Yacht Club (Deluxe) ditto
Beach Club (Deluxe) ditto
The cheapest is Art of Animation, then POR/Cabins, and the Contemporary Standard View...