You mentioned that you're not certain about the destination of your course, if I can make a suggestion, consider the Philippines. Purto Galera is good at that time, a big group of dive shops to consider and some really pretty stuff in good visibility water.
For my part, I dive with Asiadivers and Techasia (sister company), but I know and can highly recommend people from Atlantis, Frontier, Capt'n Greggs and Lalaguna Beach Club just off the top of my head - PM me if you fancy any more details.
As for a course + liveaboard, sounds great, but if diving's not for you, you're going to be pretty bored on the boat!