Given a choice between working in Zanzibar or bar hopping in Bangkok, Tanzania would win every time.
I don't know Bangkok has it's charms. Patpong being one....
If it's any help I've spent a good deal of time in SE Asia about 100++ trips to Vietnam, Thailand, the PRC etc for a few differing reasons.
A 'backpacking' Lonely Planet style trip is good fun.
It doesn't take much to spend a while wandering through Thailand, Cambodia, Laos, Vietnam and then back home via KL for example you see a lot of cool stuff and inevitably some wierd stuff and some very sad stuff...
If you're just doing the Lonely planet stuff and spending most of your time on the well trodden path then you dont need a huge bergen full of kit. The more stuff you have the more there is to nick. While folk in SE Asia are for the most part great fun and really nice. You are a magnet for folk wanting to pinch stuff. Even the poorest western backpacker is wealthy compared to some of the locals.
Teva's a selection of locally procured T shirts, underwear and shorts along with FAK with a good supply of Anti diarrhea meds and perhaps a water purifier and a good camera + recording media + Ipod ( for the bus journeys) and a sarong and a wash kit would see you right I reckon. As an American aquaintance said in there's nothing I cannot get for 10 bucks..( allow 15 for inflation).
There used to be a really great shop on Pah Nu Lao in HCMC that sold really good Backpacks and other outdoor kit... A lot branded of stuff is made in Vietnam.
SE Asia is inexpensive to travel around and if you act prudently your dollar goes a long way. If you stay off the Heinken and on the local brew Qui beer springs to mind as does Tsing Tao, life is even cheaper.
If you go have fun...
HTH
John