richard,
We were in Tampa in March a couple years back with 2 teenage sons. The highlights included the Dali museum (huge collection, big canvas, informative docent) in St Pete and The Pier in St Pete - we ate, fished with rented equipment and fed pelicans. We shopped and toured Ybor City - all the boys wanted to do there was play video games at Jillians. There were a couple places to rent jetskis around Rocky Pt where we stayed and the Clearwater Beach was quite nice. Tampa has an aquarium. Nearby is an IMAX theatre, some decent restaurants and the cruise pier.
Have fun.