My must do's are:
MK-TTA,Buzz Lightyear SRS,Haunted Mansion,Pirates,CoP,Philharmagic,and eating at Peco's Bills and/or Cosmic Ray's
Epcot-SSE,Test Track,Energy,Soarin,JIYI,American Adventure,Canada, eating at the Electric Umbrella,and generally ice cream before the illuminations show by America(although last time it was from a cart not from the restaraunt next to attraction).
DTD-We always have to eat at the McDonalds while there.Its higher priced than any McD's I generally go to but it just says to me I am at Disney/Florida. We also now tend to go catch a movie at AMC24 there. 1st was LOTR Return of the King,Night at the Museum and this last January National Treasure 2.
I haven't been to the other 2 parks since 2002 so I can't really comment on those must do's