If you're headed to Kuala Lumpur stop by my friends hostel called Mingle Hostel - http://www.minglekl.com/
I met two of the owners, Sin Leong and Steven Kap during my exploration of South East Asia and I have returned to KL 2-3 times just to visit those awesome guys. Let them know Robbie sent you and you'll meet some awesome new friends
I have not been to Vietnam yet but you totally should look into the bike tours. I've heard from so many people how amazing they are. Enjoy dude!