Phuket is fantastic, we have been 6 times and leaving in a few weeks for trip number 7 (for a 2 month stay)

Have also been to Bali 3 times but prefer Phuket by a long shot.

As recommended above, do not change money before you leave, its easy to do there.
Now for the shopping, its far better than Bali, loads more choice, the normal touristy type souvenir shopping is a bit dearer than Bali, but there is a lot more better quality goods.

I have just updated a Phuket Price Guide with loads of prices and photos of things you can buy, lots of good photos of copy handbags as well.

There also a section on things to see and do, eating out, transport etc.

A must do would be John Greys Sea Canoe Starlight Tour or a day with Phuket Sailing tours. Fantasic!
A different way to see some things is to do an ATV tour, great fun, all of this is also covered on my link below along with prices and photos.
Cathy
CATHY & GARY'S TRAVEL PAGES