Lisa,
Like you, I booked our break because I thought it would be great for my two, especially before they got any older. We were all so excited, BUT I wouldn't go back to Disney if someone paid me!!! I took my kids there in May this year. We had hopper tickets for 4 days and it took the kids some persuading just to go back a second day. They hated it and still tell everyone how rubbish it was. We didn't bother going back the other two days.
It's a total rip-off and all about them making money. Even back then in May, when it wasn't the French or British school holidays, there were queues for the very few rides there are. Most of the park is made up of shops (all selling the same, over-priced Disney tat), restaurants and places to stand and queue for very few rides. You wait forever in queues (the fastpasses were longer, they expected you to come back e.g. 3 hours later rather than wait 20 mins!) for rides that aren't that good and over far too soon.
The studios tour didn't take long either. My kids - age 8 and 10 - were crying with disappointment and I barely saw a single child smile the whole time in the 2 days we were there (got rid of the other 2 day tickets when we got back). They said our local theme park is better. We all agreed that 'It's a Small World' was the only really good ride of the lot and my little boy liked one of the roller-coaster type rides, but aparat from those two - I mean, you expect a theme park (never mind Disney) to be FULL of good rides that you get to try out in a day, don't you?
Another thing is that the toilets are very spaced out and were quite dirty/stinky when we were there. At one point, I really needed the toilet and couldn't find the next block of toilets on our walk through the park, so tried to use the toilet in one of the restaurants, but a woman barred my path and refused to allow me (even though I was noticeably pregnant). That pretty much summed up the attitude of the staff there. They discourage you from eating your own food by having tables and chairs next to kiosks and restaurants (most of which sell horrible, fast food).
I would completely avoid Disney altogether and go to the French theme park, Parc Asterix, instead. It's a beautiful theme park - very picturesque, with plenty of green places to sit and have your own picnic. There's a lake and some trees too. It has lots of grass and benches to sit. It has ride after ride, nowhere near the same queues as Disney. The staff are friendly and the shops reasonably priced. They even have a free dolphin and seal show and a chance to meet the Asterix characters.
To compare the "rip-off-ability" - Disney charged something like 22 euros for a photo taken of you on a ride, whereas Parc Asterix charge about 7 euros. Parc Asterix seems to have much more rides - and they are all more exciting and last longer. Kids are laughing and enjoying themselves.
Sorry to go on - as a family, we HATED Disney and I now just want to tell everyone visiting Paris to go to Parc Asterix instead. In fact, my kids even got more excited seeing the real Mona Lisa in the Louvre than they did at Disney!
You'll have to go, just to see it for yourself, but I'd advise you just to buy a 1 day ticket and keep your options open as to whether to go back another day.
Perhaps you'll love it!