Like everything in the Keys and especially Key West, things are expensive. If you are coming back all the way from Ohio, treat yourself to Bluewater Key. Most of the sites are waterfront and all have Tiki's. We prefer the canal side as the winds are much milder, on the bay side it can get too windy to enjoy being in the tiki.. just depends on the time of year and weather.
While you may save a few $$'s staying in Marathon, you;ll have an hour and a half drive , each way, to Key West.... not something pleasant to do after a long day/night in Key West.