I believe that Holiday Inn is on the east side of the island, which means it would have been the opposite side of where the tsunami struck. Right?

I have heard first-hand reports that most structures on the developed areas of Phi Phi (Ton Sai and Lo Dalum bays) were almost completely washed away, like nothing was ever built there. Presuming Holiday Inn (and presumably PP Island Village) on the east side are all that's left, there's not going to be anything on the rest of the island for you.

On another site (www.travelforum.org/thailand) I have read that Ao Nang/Krabi weren't hit as hard. Might be an alternative for you. I've read mixed information about Ko Lanta. You might try the Gulf side of Thailand, depending on the timing of you trip and the Gulf's monsoon season.