Of course you can find those rentals, they're all over the Pinellas beaches and many offer 3 month leases more or less... some you'll actually get a 3 month, while others will be a month to month agreement. The most difficult part is finding the place you want this time of year as many are "booked" well in advance. When were you thinking of leasing? That is to say the Winter is "in" season and parts of Summer, mainly around the holidays. What a friend of mine did in to rent a 3 month in Ft Lauderdale was to simply get a copy of the ads via online newspaper, surfed Craigslist, but ultimately she found one for the family from a property management company who was really helpful and provided a list of properties.