Man, that's an awesome sounding trip! My and my missus will be heading that way in September (all booked up), although, i'll be going for 6 weeks and she will be going for 6 months!
Will be flying to Bangkok, doing a ten day trip through Cambodia "roam Cambodia", into Vietnam, up that coast, pop over into Laos, ending up into Hanoi where i'll be bidding farewell to my other half and heading home.....unless work goes pete tong and if that happens, i'll be going for 6 months!
Hope you have an awesome time dude!!