If your idea of a fantastic vacation means being by the water, make tracks to No Name Key. Whatever you choose to do here, you're unlikely to tire of those pretty views.
You're spoiled for sightseeing choice in Big Pine Key. No Name Key is a good place to begin here, but there are lots of other interesting places to appreciate. Bahia Honda State Park, Calusa Beach, and Big Pine Key Flea Market are not far from the water-surrounded land mass and will top off your day nicely.