You can always look into multiple family suites (Art of Animation or All-Star Music) or Fort Wilderness cabins, or even 2-3 standard rooms, connecting if possible, at the moderate resort of your choice (Port Orleans Riverside, Port Orleans French Quarter, Caribbean Beach or Coronado Springs).
However, depending on the party's configuration and your budget, I'd suggest looking into renting DVC points for a dedicated 2-bedroom villa, perhaps at Wilderness Lodge, which is conveniently located and one of the least expensive DVC properties. (Multiple studios, especially at the Polynesian, which has 1.75 baths in each studio, would be another option.) A 2-bedroom villa would give you a bedroom with 2 queen beds, a living area/full kitchen with a double+-size foldout, and a master with a king bed and plenty of space for a toddler-sized cot or air mattress, or in some cases, a built-in Murphy bed. There are even larger, "grand" villas at some resorts, but the prices get pretty astronomical... the points/price chart at the DVC rental company websites will give you prices for every option.
We've had good luck with David's Vacation Rentals, and I often see the dvcrentalstore reviewed favorably here, as well. The downside of renting DVC points is that there's no option to cancel, so you'd have to purchase separate vacation insurance to cover the cost in the event you had to change your plans. The upside is that you can save a ton (we saved 40% off the rack rate for our 2-br villa at VWL, and will save 25% on upcoming studio rentals at BCV and Poly) by renting points instead of going directly through Disney.
