Talk with a local builder but would also like to recommend you speak with a local agent or Realtor. I do not know the market there, but here in Tucson AZ there are a lot of inventory for buyers, thus a buyers market. New builds are at a low.
Also, please consider speaking with a lender, buyers are finding out getting a new construction loan in this market is not easy to do.
Furnishing a short term rental isn't as much about "style" as it is good taste and cleanliness. Buyers of rental property in Florida enjoy a great supply of reasonably priced and good condition furnishings that can be found easily at consignment and secondhand shops.
Light colors and the tropical look are always popular with Florida renters......and you can never go wrong with birds, fish, boats and golf accents.