Well, Southeast Asia is pretty diverse...it would be better to know your itinerary. E-mail me if you have any specific questions. I live in Indonesia, and have spent several years trundling around here. Aikido can be found in SE Asia, but certainly does not reach the level of dojo density as exists in the SF Bay Area.
The only general pieces of advice I give to people from the US is that we still like your dollars, and to have activated carbon and insect repellent handy.