I would think it is much better to get a mid level hotel or condo, and spend the savings On a Boat rental.
One of the best things about the boat rentals is the fact that you get to go to the bars on the boat. Nothing is more enjoyable than cruising the waterway system of the Florida Keys. I love going slow and looking down into the water. The upper keys has a bunch of very nice boater friendly bars to stop and dock.
Just tie the boat up at the Big Chill saloon and head on in. It is a huge place with a separate sports bar inside for Monday night football and the big outdoor tiki hut area, with a Great View and a restaurant for poolside pleasures. I like the salty dog grapefruit vodka, but take your pick of all sorts of yummy drinks like the electric lemonade smoothie - raspberry lemonade smoothie - bone island iced tea - keys sunset - sex on the border - or a Florida Keys mojito cubano! Walk to the bar from the Key Largo Marriott and the tarpon flats inn and marina.
107690 Overseas Highway
Key Largo FL 33037