Is a really cool town. We stayed at Treasure Island beach and it was not crowded at all.
Naples has beautiful beaches and incredible restaurants and shopping. Its a beautiful, rich town. Even the Walgreens building is pretty

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St. Pete is more cool and artsy. I loved the vibe and the wonderful downtown and restaurants. We took Segways with a guide and had a blast and got to see the incredible boat harbor, etc.
Make sure to take a sunset cruise. Not on one of the party boats, but a cruise company. The one in Naples, is unbelievable. It takes you all down the Naples bay out to the Ocean, and then turns back. You will see so many mega mansions and mega yachts. It was my favorite part of the trip. You don't have to take it at sunset. They have them a couple of other times in the day.