Since you'll be at your Tampa hotel by 4:00PM, without a car, you may want something to do. Renaissance by the airport has the International Mall and a selection of restaurants. Hertz is also available in the lobby, or a shuttle to TPA. I doubt if breakfast is available at 6AM.
There are also several hotels facing Tampa Bay, at a variety of prices, if you'd enjoy the view. Pricing should be reasonable with all the competition.