We've done it twice - once in Feb., once at Christmas. At Christmas the manatees were everywhere, in Feb. we still saw them, but there were fewer of them. We rented a boat ourselves instead of doing a tour. There were 7 of us, I think we stayed out around 3 hours and it was pretty inexpensive (we did not rent wet suits, the air and water was warm enough without them). It is incredible when you see one of them lumbering up to you, I'll never forget the sound of my daughter's squeals of delight through her snorkel tube the first time one came up to her! If you'd like more info, pm me and I'll dig out who we rented from (last time was in 2002 so I can't remember off hand, but I have the receipts and stuff tucked away somewhere!) and the cost.