MK:
I know it's not one of WDW's prime attractions, but when DW and I went together for the first time in 1986, the first attraction we went to was the Enchanted Tiki Room. Since then, we've become a bit more savvy and join the mad dash for Space Mountain when the MK opens. But we try to get over the the Tiki birds soon after.
Epcot:
Spaceship Earth
MGM- er, I mean Disney Studios:
ToT/RnR (FP for one, ride the other)
AK:
Kiliminjaro Safari's