just stumbled across this in my bookmarks this morning - you couldn't ask for a more complete guide to thailand's various islands!

http://tezzasthaiinfo.blogspot.com/2006/12/ko-phi-phi.html

the "which island or beach" section is probably what you're after:

http://tezzasthaiinfo.blogspot.com/2007/06/index.html

it breaks all the islands down w/regard to their strong points, hassles, current prices etc. especially helpful are the reviews of the islands beach by beach... hope this helps!

-mw