Just Discovery Island for me. It was only open on my first trip to Orlando in 1998, however I don't think we knew about it at the time.
Apart from that it was a pretty packed holiday trying to see everything in 2 weeks including the then 3 parks, TL and RC. IIRC BB was closed for refurbishment. Also a day at Universal, Seaworld, Busch and Kennedy SC. That's 9 full days, not bad in what is essentially 13 full days. I am sure we returned to some more than once. Definitely did MK twice as my first day there was January 2nd, it was really busy but I remember going a few days later and being shocked how much quieter it was.
