Looking for recommendations on travel in southeast Asia?

I am in the process of planning a few hiking trips. As could be seen from a previous post I made, I need to travel and break the shackles of work/life. Thinking sometime next year.

So I think I may hit Southeast Asia. Thinking of hitting the "Ho chi Minh Trail". I spent a while touring some of Vietnam a few years back., always wanted to return to here and Cambodia and maybe check out this trial.

So if any of you travel guys/gals out there could give me some route advice/time of year/what to avoid etc... I would really appreciate it! I am also a huge history dude- love to experience some of the histories here, can image some harrowing stories. I also plan to take a lot of photos and share here, if I make it there!