something about the accomodations: I've stayed at a few places on phi phi between april 05 - feb. 06. 1st off, the "touts" at the pier are quoting you the same price you'd pay if you went to the guest house, though if you're planing on stayin for over a week you should inquire about weekly rates, almost everyone offers monthly rates. if you do go with the guys at the pier make sure that the place they're offering you is in tonsai (town) and not on longbeach, though longbeach is nice its also quiter. a great thing to do when you arrive is drop off your bags at one of the dive shops (you wont be committed to dive with them, theydo this so you'll have a good impression of them when you look for a shop). My suggestion is to go towards viewpoint (not the resort but the hill) and look into the places there - they're typically cheaper (fan, cold shower). you have harmony house, us guest house, tropical gardens - bamboo huts and pool, uphill cotages - where i lived and phi phi dream - cheap but not great.
also at the edge of the resivoir you have 5 possibilities: rimna villa which are rickity bungalos but should be well priced as well as "the rock" which are dorm accomodations - look for the big boat in the hillside (constructed, not tsunami related

. you have amena, which has nice rooms though they have two different sizes and charge the same for both also you have la casita which is a bit more expensive but they also have a frig and tele, valentines is at the same corner and are quite nice as well.
of those i've stayed at uphill, tropical gardens, us guest house, amena and valentines so if someone at the piers offering you one of those go for it, you can always say no thanks and grab something near by.