So hard to say what attractions they will like, as all kids are a bit different. My girls have always loved the shows and attractions with strong character appeal (i.e. Little Mermaid), the classics at Fantasyland, street shows in Epcot, making masks at world showcase, and character meals. Oh, can't forget AK. Of the evening attractions Fantasmic is their all time favorite. As soon as it finished my youngest daughter always wants to watch it again!
It is best to have realistic expectations as very common for children your age to prefer the hotel and pool over the parks. We find it best to head out early in the morning and then back to hotel/pool for a break once the girls get a bit tired.
Your children are a great age so you will have lots of fun if you take it easy and go with the flow. There's so much you will want to do, that it's hard to just let them guide you, but this will give you great memories. A few years ago when our girls were that age we hit MK on arrival day. After eating hotdogs at Casey's it took almost 45 min just to walk the short distance to Adventure Land. We had to stop, listen and talk to the piano player, then stop each and every time there was a bird or other living creature. Let me tell you, that has become one of our favorite all time memories. At the time we joked that at that pace we would barely get through one park by the end of the week.
