I would strongly advise AGAINST staying at the airport. The airport is very far out of town (by train around 45 minutes, and that's assuming you are anywhere close to the train station), it would be a pain to get back and forth, plus quite expensive (17 euros per day per person round trip). You should definitely look for someplace inside the city close to a Metro, as its pretty simple to get anywhere from inside the city as long as you are nearby a metro stop. There are plenty of Holiday Inn's in the city.

Just to overemphasize, the airport is the absolute worst place you can possible stay for seeing Paris. (Hopefully that will be convincing enough )

Also to your original question, I would recommend that you only do one chateau outside of Paris (e.g. Versailles). There are sooooo many things to do inside Paris, taking the daytrips (and they are usually daytrips) kills a lot of travel time.

Luckily, Disney is not difficult to reach from the city, as there is an RER train that takes you from central Paris directly to the front gates of Disneyland!