Scuba diving in Asia forum

We're actually giving away a PADI course on Ko Tao today -- more information here:
http://www.travelfish.org/travelfish-turns-five.php

Smash,
I don't have any personal input on those options but did dive with Scuba Junction, which included 50% discount on accommodation in high season. Not sure what the deal is in low season.
The instructors there were amazing. My partner was taught by Ayesha, who's involved in the Travelfish giveaway this weekend. I cannot say enough positive things about Ayesha and her approach to diving. I'm already certified, but from watching and listening to my partner, I was incredibly impressed by her ability to make the course fun and, at the same time, be very safety conscious, which should not be under-estimated.
Do you absolutely need to book ahead? What time of year will you be there? It's really best if you can show up and meet your potential instructor before committing to a school so that you can make sure that you will be comfortable with him or her and there are no language issues. I firmly believe that you should have an instructor that is completely fluent in your native language because if you don't understand each other, it can have disasterous consequences. I've dived when there's language issues, and it's not smart or relaxing.
You may also want to check out your accommodations before committing. Some places are known for providing "free" rooms that are awful. Keep in mind that the free rooms are the most basic and least desirable rooms the resort has to offer. Depending on your budget, it might be better to get 50% off a better room. Or at least check out the "free" room to make sure you can sleep there. Scuba diving isn't fun if you can't get a good night's sleep.

I think it depends on the time of year and your travel style. We showed up on Boxing Day - peak season - late in the day without reservations and were fine (although accommodation was certainly tight). There are so many dive shops and resorts that if you don't have your heart set on something in particular, and are flexible, you're probably fine except in peak season, and even then, we did fine.
Keep in mind that tourism generally is way down in Thailand this year. That doesn't mean Ko Tao will be deserted, but it may not be the crushing crowds of yesteryear.