We were on Pawara, the second boat StevenL mentioned, a couple weeks ago and were quite happy with it. Went to the Similans, Koh Bon, Koh Tachai, Richelieu Rock, and two dives on the Boonsung wreck to finish off the trip. Richelieu was our favorite spot. Have done better diving elsewhere, but it was still a fine trip. Pawara's current dive staff and the Thai crew were great, and the food and accommodations were good as well. It's apparent the diving on this itinerary isn't what it used to be though. Trip leader Marco would always tell us what they used to see at each site that they don't anymore, and I could have done with hearing less of that. Would have loved to stay at Richelieu for the last two dives instead of going to the Boonsung, though perhaps it wouldn't be feasible time wise. One thing worth noting for someone who's been on a few liveaboards -- this one is 4 dives a day only, no option for a 5th night dive like many liveaboards elsewhere offer. In fact, the first day is the only one with a night dive. On the other full days, you finish up around twilight. Not a big deal in my book, as 4 a day is fine with me, but some people like to maximize their time underater. We had one of the two master cabins, the priciest on the boat, and it was more than adequate. Didn't get a chance to see any others, but heard no complaints from anyone on the boat. Get in touch with Steven if you have other questions. We booked this trip and a day trip earlier with him, and I highly recommend him.