Buy whatever you want. It's your money! My advice, however, is to buy postcards and take lots of pictures. Just remember that whatever you accumulate during your travels must be lugged around and transported home.
'Boat tour' at Tarpon Springs - If you are looking to sit down and relax for 1 - 2 hours, this is an OK thing to do. However, there are only a few medium - sized houses and a lighthouse to see on the trip. (Nothing very unusual or exceptional.) If you are pressed for time, skip this one.