I'd love to stay in an onsite Hotel.
Before we bought AP's we stayed in Davy Crockett Ranch (when it was just us 3, before our son was born).
Since we have the Dream AP's we stay in an appartment we found initially via tripadvisor.com in Bailly-Romainvilliers, but now we just email the owner and tell her when we want to visit. We pay €85 per night for a 2 bedroomed appartment, with a large living room, kitchen with dishwasher, washingmachine, fridge, oven, microwave, a large terrace by the water and a private parking place underneath the appartment.
I cannot justify paying almost double for an onsite hotelroom where the four of us are cramped into one bedroom - not to mention the fact that it would make our five week-long-stays a year financially impossible!