Agree with dansyr MGM has the best two thrill rides TT and Aerosmith's RRC also see at least Star Wars, Muppets 3D and the Indiana Jones Stunt show while you're there. Fantasmic is good but it takes the entire evening.
At Epcot, Test Track & Honey I Shrunk the Audience are must see! (I also like to drink a few beers of the world while I'm there
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At MK all the Mountains are a must! Space, Thunder and Splash. But while you're there I'd see Haunted Mansion, Pirates and Alien.
At AK Tough to be a Bug, Countdown to Extinction and the white water River ride.
You will not be able to see half of what's there in 3 days at 4 parks so be sure to use the Fast Pass efficiently. For instance, at MK get a FP at SpaceM. It will list a window say 10:00 to 11:00 about an hour or more away. Go do something else until your time. But before going on SpaceM go get another FP at say SplashM @ 10:01 then go ride SpaceM. Then before you go ride SplashM got get another FP.
PI is pretty good at night but a few of the places are hard to get into once things get rockin'. I'd suggest the Comedy Club's first show followed by the adventure club. Then it depends on your age and taste. BET for hiphop, Motions for Pop, etc.
If the boyfriend or you like video games do Dis Quest during the day and PI at night. If not skip the quest. Do your shopping in between since all three are right there together.
If you want to do the Boardwalk you can exit the back gate of Epcot (Between England and France) and walk down along the River. You'll come to the Beach & Yatch Clubs on the right and the Boardwalk on the left across the bridge. The river connects Epcot and MGM by boat and that area is great to cruise around.
My DD went to W of Sports last time to watch some boys play soccer. I got the impression from her that if you don't have something specific to watch there it could be passed. On the other hand if the Disney BF likes sports there may be something going on worth watching.
My 2 cents