Key West is remote and accessible at the same time. Located at the far end of US Highway 1, it's a spectacular 4½ hour drive from Miami (that almost always takes longer because of all the cool things to do and see along the way). By boat from Miami takes at least 3 days. For the less adventurous, it's only about a 30 minute flight from Miami Airport (though the walk to the farthest gate, from which the flight leaves, can take awhile, especially if you are tempted to stop at any of the shops and restaurants that line the corridor). And, of course, for those who think an adventure is open-seating, cruise ships do stop here. However, they don't usually allow you to stay long enough to be interested in a rental.
The most common way to get there is by automobile. Google Maps can help with that.