V.B.
EDITED TO ADD:
The Florida Aquarium is in Tampa if you're up for something like that. It is a little bit of a drive, but not too bad. It's really a pretty awesome aquarium and they have a splash park outside for the kids, so they might enjoy that. It's in an area in downtown Tampa called Channelside. There are some restaurants and shopping and stuff there too. Just something else I thought of seeing the other posts. :-)
DEFINITELY Frenchy's!
I've never done the pirate ship thing, but the kids might enjoy it (not sure how old they are). There are other boat tours you can go on that are great, especially the dolphin ones. The kids will surely love that. Beyond that, just enjoy the gorgeous white sand beaches. I grew up in Sarasota (Siesta Key was just ranked the #1 beach in the nation....that was "our" beach) and I miss it so much now that we live in TX. I definitely took it for granted when we lived there! We're moving back to FL this summer (although to south Florida) and I fully intend to visit the beach a lot more often now that I realize what we were missing! :-)
Have fun!