Yes, we are Grand Slam Plus members! (All 4 Disney ships plus the Big Red Boat). Sadly, we'll be out of that club shortly with the Wish, but will rejoin as soon as we can.
Anyway, we sailed in 1991 in the ship's premiere suite (forward starboard). It was a land/sea package, since we were in the suite we stayed at the Grand Floridian for the land part. I remember lots of Disney Characters and activities for the kids. The ice cream bar by the pool seemed open al the time (probably not, but that's what we remember). They did have a midnight buffet. I can't remember the private island we used for the beach day, but we did tender to it.
Those were the days of the straw market that later burned down, resulting in the big tent straw market on the water until then later moved to their present location. The on we visited in 1991 was kind of near where Senor Frogs is now, IIRC.
We watched the crew fishing off the boat every night and catching many, many fish. They probably had the freshest meals onboard!