so much today:
I went, Bangkok to north Thailand, into Laos doing the Laotian
loop and then to Champasak in the south. Back to Bangkok and then
through Cambodia, and into Vietnam (Saigon to Hanoi). That took
about 2 and a half months. This is the easiest route.
You can go Laos to Camboia, but the border situation is constantly
changing, and it takes a few days to get anywhere.
Later I flew into Bangkok again and headed south (Krabi, Koh
Samui, ...), through Malaysia and into Singapore. I didn't do
Indonesia, since it's so big it takes a couple of months to do it
justice. But it's easy to get there from southern Malaysia.
You can fly to HK easily from Hanoi, but if you have the time why
not travel overland from Hanoi to HK? Crossing the border was easy
when I was there last year.
One suggestion is Borneo. I loved Sabah, it was a definite
highlight of my year. You can get really cheap flights from Kuala
Lampur on Air Asia. I paid 99 R each way (about $25 US). You could
fly into Sandakan and travel down to Kuching (via Brunei). A great 2-
3 week trip. If you don't have the time, at least consider one week
in borneo, Sandakan to Kota kinabalu is do-able.