Coastal Towns in Tuscany?

Several choices depending on what kind of coastal towns you'd like. I'll give you some suggestions. Use Google Image to search the names I give you for photos of each and decide on what you'd like best. My favorites from North to South: Versilia area: VIAREGGIO, FORTE DEI MARMI (and any towns in between). This area is in a flat coastal plain between the Apuana mountains (Carrara marble) and the shore. The beaches are sandy and reasonably big (like in Florida). They are very popular resorts full of hotels and fancy promenades where vacationers stroll all day and night. Viareggio is the most popular. Forte dei Marmi is very upscale and you are likely to see some famous star in town (the singer Sting, and a lot more VIP, has a villa there). Versilia is where I used to spend my summer vacation as a young kid. It was perfect for kids that age. Plenty of entertainment and "chicks" galore. Livorno area: QUERCIANELLA and CASTIGLIONCELLO. Fancy resort towns. Pretty landscape with mountains jutting out to the sea. Beaches are rocky, since it's more cliffs (similar to the Cinque Terre). Elba island:
This is not doable in a day only. You need to go to Piombino (or Livorno) and catch a boat. But it's beautiful, so I'll mention it. continued to next comment.

Lastly Grosseto Province area. This area is beautiful, but maybe not close enough for a day trip. PUNTA ALA, CASTIGLION DELLA PESCAIA. All gorgeous resort towns. Punta Ala was a new development full of fancy timeshares and yacht harbors. Great beaches. Castiglione della Pescaia, nice old town. Fancy place also. A childhood friend of mine had a villa there, so I visited sometimes. Roger Moore (the former James Bond actor) was her neighbor. He had a villa there also where he would vacation with his Italian wife (Roger Moore speaks perfect Italian). TALAMONE: Great location next to the Uccellina National park. Nice harbor town famous for weapons construction and arms trade. Garibaldi stopped there to get weapons for his campaign to conquer Italy. During the Iran-Contra affair in the 1980's, arms and war equipment secretly destined to the Iranians (from the US) passed through there. I have a picture of myself behind Army trucks on the loading dock during a weekend visit in the 1980's. They had writings and license plates in Farsi. I had no idea they were part of a scandal that would engulf the Reagan administration just months after that vacation. http://www.waymarking.com/waymarks/WM4F1M_Bagno_delle_Donne_Talamone_Italy ARGENTARIO PENINSULA, PORTO S. STEFANO, GIGLIO ISLAND.
This is truly gorgeous. But probably too far from Florence for a day trip. If you only have a day (from morning to evening) you're better off sticking with the Versilia area or with Quercianella or Castiglioncello south of Livorno.

@Roberto... these are some names I need to file for future use (sounds a bit like Roberto's 'road less traveled' suggestions) They all sound fabulous.