we stayed at a super plush place in key largo for like 2K for a week. was a very “baller” place, however the keys don’t really have white sand beaches.
mostly just went to the resort pool that had sand around it. It was right on the ocean, just the keys don’t have much beach-wise.
it was cheaper because it was off-season so it’d probably be around 3K peak seasons.
http://www.marinersclubkeylargo.com/marinersclub/KeyLargo/klphoto.aspx?MenuId=05
just sat around in hammocks and drank all day while i was there, was great. you can do a day trip to key largo for fun, snorkel or scuba. thats all we did really
edit: IIRC its the only 5 star resort in the keys