There are lots of levels depending on your personality.
1) Big Boat, lots of people, big separation from the "wild animals"
2) Small Boat, just a few people, more expensive, but you get closer, maybe even touch them
3) Swim/Snorkle, just a few people, very expensive, in the water with them, definitely touch.
My wife voted for big boat because she wanted the separation first time, but said after seeing it, maybe the little boat would have been better, but still didn't want to swim with them.
Gauge your level of adventure / contact.