Hi babylonsister!
Phuket is really lovely, the beaches are much prettier than Hua Hin. I've stayed at both Kata and Karon beaches, which are beautiful, with lots of yummy places to eat beach front. Hat Surin in the northwestern part of the island is also lovely, more secluded and quieter, but I was there before the tsunami so I don't know what it's like now. My impression is really that these places have all recovered, though, so I think you'll be fine in Phuket.
Number one piece of advice: Avoid Patong beach like the plague -- there's nothing there you want to see, it's the grossest, most over-developed girlie-bar part of the province.
Sorry about the Lonely Planet, I thought they had a new updated version. The Rough Guide to Thailand's Beaches and Islands is also supposed to be quite good and probably picks up a few nicer spots than Lonely Planet! The internet though is probably the best source, you just have to check around to make sure (a) you're not getting ripped off and (b) the place is as cute as it looks.
www.travelfish.org is a really reliable source, and has good reviews from people who have stayed at various accomodations in the past, and they have downloadable (you have to pay for them) little guides that are quite good, here's the one for
PhuketFrom Phuket you can also really easily take a longtail boat over to Krabi (Rai Leh beach is really fun for rock climbing, sea kayaking and so forth), Phi Phi or even Ko Lanta, all of which are a bit less developed and more low key. It depends on how long you are there, though, as it means losing a precious half day of lounging on the beach!
Also, just because I think it's funny when I hear tourists mispronouncing it, the PH in Phuket isn't pronounced as an F like it would normally be. It's pronounced P (a bit aspirated). So, it should really be spelled Puket. Just a helpful tip though you may already have been well aware of this factoid.
Good luck! Keep us posted!!
Jean Louise