Hi Julie,
I think it might be too tight. The convertible sofa bed is only a full size. Your kids might find it uncomfortably small. The rooms are bigger and nicer than those at Port Orleans. If cost is not an issue, I would recommend the Villa.
You may want to look at Old Key West which has a sleeper sofa and an extra couch. One child could sleep on the couch while one slept in the bed. Also at Animal Kingdom Lodge, in the living room their is a chair that converts to a single bed and queen sized sleeper sofa. Most of the other Deluxe Villa have one king sized bed in the bedroom and a queen sized sleeper sofa in the living room.
If you do not need to stay in a deluxe villa, you may want to consider getting two rooms at a moderate resort or value resort.
Another option would be to get a cabin at
Fort Wilderness. There you have a murphy bed and couch in the living room.
If you have any more questions just let me know. I've stayed at all the resorts I mentioned above.