Listed here area a few examples of extremely luxurious over-water resorts. They say 2/3rds of all such resorts in the world are in the Maldives! So even though I'd love to vacation in the Carribbean, Turk and Caicos islands or Hawaii - I may consider a trip further east to experience romantic isolation in one of it's most unadultered forms :)
http://www.cnn.com/2011/TRAVEL/05/11/five.overwater.bungalow.resorts/index.html