I don't recall a Starwood or a Marriott in the general area of Busch Gardens. Though there are a few in Tampa - there's a Sheraton and a Westin at the harbor and a Sheraton just off I-275 near the airport and the International Plaza shopping mall, and Marriott has a hotel at the harbor, I think there are two Renaissance hotels in the airport/International Plaza area along with a Towne Place suites, a Residence Inn and a Springhill suites, maybe a Courtyard, too.
That Grand Suites that Doom1001 mentioned (which, incidentally, was a Doubletree suite hotel when we stayed there four years ago) has changed affiliation again and is now a Holiday Inn & Suites. I also remember that as an okay hotel that had its best feature as being really close to Busch Gardens - less than a five minute drive from parking lot to parking lot - but not in a great area of Tampa. With that said, my daughter and I felt quite safe there. I'd assume that with two reservation system changes since we were there that there have been facility improvements to what I thought was an already acceptable hotel.
Dick Taylor