i have been on one LDS planned trip that cost three times more than the one I planned myself to the same location, but a better hotel. It's not that much work, you can find so much on the internet, tripadvisor and agoda are great for giving you good reviews on most places and accommodations. Some places like when i went to Koh Lanta to start my adventure in scuba diving, the dive shop just stood out. They weren't a big fancy school, didn't have a huge pool, but their individual attention, their great dive boat, and the well run, efficient way they run it were impressive. And because of that, I went back and got my OW cert from them, and in Feb, we will be back diving with them again..
Point here is that you can find good shops by 'shopping around' and asking people... if the shop doesn't like it, TOUGH.
And if you are in the mood for a good time, look up Andaman Dive Adventures if you get to Koh Lanta in Thailand, you won't regret it