Well, 1 down and 4 to go...just booked the boat daytour on the first full day. I guess I can plan to do the postcard mailout out of there as well. There's also the manatee rescue center as an idea, though I saw somehing along those lines in Florida. Am also there on a Friday and Saturday, which is supposed to be a good time to be there.
Sometimes these trips are useful if for no other reason than to motivate (or discourage) more-ambitious subsequent trips. I'd need some selling with some of the prices I'm seeing on some multi-day expeditions, but OTOH a number of 'em with the company for the daytour are already sold out anyway. I guess others going there have more money than me.