N.,
We have gone to Disneyland Paris twice. We have four kids 11, 5, 4, and 7 mos. We have loved it both times. We stayed at Davy Crockett Ranch and even though it is not right on the park or the nicest (very clean and rustic) I would always choose to stay there. I love not sharing walls with others (loud kids), each cabin has its own driveway so you aren't hauling tons of stuff through a hotel, each cabin has its own kitchen. Since we drop 50 euro just on burgers and fries in the park we like to save our meals in the park for something special and eat at least lunch or dinner in our cabin (they even have an outdoor picnic table). Every morning you go to a little cabin and pick up a breakfast of croissants, baguettes, juice, milk, etc... I bring fruit and yogurt to help fill us up and give the meal some nutrition.
As for the park. I would definitely recommend at least two days, we did three once and four the other time. Those are good too:). I just have found that stressing out about trying to fit it all in and going from opening to closing (stateside) made all of us a little cranky. We try to get there early, maybe take a break in the afternoon (you get a parking pass), do a late lunch or early dinner, and then go back as crowds start thinning because everyone is exhausted. If you only go for one day, start early, stay late, look for something other than rides to keep you busy in the afternoon.
Be prepared- people absolutely swarm the characters. We tried to see Minnie and it was unreal, everyone is really aggressive. I don't know why. We have always loved seeing the princesses (three girls and a baby boy) but we did not even try after Minnie, we just watched in amazement- from a distance.
We have booked both trips through the website. One was for block leave and one was for R&R. It is just a nice place to enjoy being with your kids and having fun, remember that you will be dealing with some serious lines. We put together some things to do in line with our five year old- she can't hold still for a minute.
I hope this helps.