Hey! When I was booking my holiday to Disneyland I came here for information, so I just thought I'd note down how our holiday was in case it may be of any value to someone. 
I went with my son and booked a hotel for 2 nights to go to Disneyland for 2 days and get on the Eurostar home on the second evening. Two days at Eurodisney was plenty for me.
I think if I were to do it again, I'd just book the hotel for the third night and let all the stress of meeting the Eurostar on time be left for the next morning since I ended up rushing onto a taxi and spending extra money anyway! Also I'd probably book the Kyriad hotel at Torcy which was more expensive that than the one I stayed at but would have saved me a lot of extra time finding buses and walking.
My son is 3 and the queues were difficult for him. We waited from 15 mins (even when it said 5) up to 60 mins for rides. I gave up on any hopes of him eating healthily and chose queues for the time to let him eat, stashing snacks, bottles of water and goodies in my handbag! Also we got very cold in the queues and needed our zip up coats that were easy to slip on and off.
There are all the great rides that I remember from my childhood, the obvious ones like It's a Small World, Tea Cups, Le Petit Train du Cirque... and I went on the Pirates of the Carribean boat ride with my son which was a bit dark and scary but lots of fun (he loves pirates).
We went to the Walt Disney Studios and I had no idea what to do there not having been before, but if I were to go again I'd probably rush straight to the Crush Coaster, Cars, Magic Carpets, Slinky Dog, and the Toy soldiers parachute drop... The Playhouse Disney live on stage was ok - my son seemed to enjoy getting up and dancing and clapping, plus they had bubbles and gold streamers dropping onto the audience at one point, it was a rest for me!
Finally, forget about having a cup of tea whilst at Disneyland because I waited in the queues for ages and it really wasn't worth it! Bottles of water were much more appreciated.