sillyminny, there are two rides at SW ~ Kraken and Journey to Atlantis, both fun if you like thrill rides (we do) and don't mind getting wet (JtA). The SW website will also give you a list of all the marine exhibits and shows. We find one day plenty, but it really depends on how long you want to spend at each attraction and whether you can fit in all the shows as well. We find feeding dolphins especially fun and tend to stay quite a while at Key West Dolphin Fest.
SW is a very pretty park to wander around and a nice change of pace to Disney and Universal. We were there during March Break and the Christmas holidays and it wasn't too busy, which made it all the nicer. We were able to walk-on Kraken several times in a row, before our stomachs said "enough" and we were dry from JtA.
If you want multi-park tickets there are Busch Gardens/SW combo passes and a 4 or 5 park Orlando Flex ticket (SW, Busch Gardens, IOA, USF, Wet n Wild) available or keep checking with a
travel agent for any Canadian specials that should start this fall, if it's the same as last year. Also check in the fall Florida travel brochures. I can't remember if there was anything mentioned about the Canadian special at the various park websites.