You lucky thing!

We just came back from Phuket a couple of days ago.  If you're going to
be in the Kata / Karon region, I would probably recommend using Sea Fun
divers, based in Kata Noi
<http://www.seafundivers.com/daytrips.htm>

We spent 4 days diving, one day with Scandinavian Divers, a 2-day
liveaboard with Similan Prodive and a one day with Sea Fun at Phi Phi
and I can safely say that the service and procedures were noticeably
better with Sea Fun.  Also, that was the only boat that provided cold
bottled water and cold coke / sprite as part of the package.  If you do
go there, say hello to Boris and the two Andy's for us please.

Also, one thing to note is that they all seem to use each other's boats
and services, so you might book with one centre, but end up on a
different centre's boat for the dive.  Make sure you confirm who you're
going to be diving with.

Hopefully you'll have better visibility than we did.  Over the past
month visibility suddenly dropped from 30m to about 15-18m and on the
King Cruiser wreck, we only had about 8m, but sea life was still
abundant, leopard sharks, turtles, cuttlefish, sea snakes, morays etc
etc