Southeast Asia forum

With this possible route I'd say Vietnam, if anything for cost. It is almost always cheaper to fly into and out of Hanoi or Ho Chi Minh City than Cambodia, Laos, or Northern Thailand - though the cheapest flights to the region will often go into BKK if you are flying non-stop from a European or North American destination. However, if you layover in Hong Kong you can get flights that bounce into Hanoi or HCM for a good price from Cathay or other airlines.

If you start in Hanoi you can go into Northern Laos and cut over to Chiang Mai - then fly down to Siem Reap or Vientiane (I assume that flight still exists) to work your way down to Siem Reap through Southern Laos. From there work through Cambodia, maybe checking out the coast, and over to HCMC and the Mekong Delta if you want a wide loop and back up the Vietnam coast to fly out of Hanoi. Any number of possible variations on this by heading south first down to HCMC or flying into HCMC first and reversing the path. I only recommend the northern route first because it can be colder and dirtier, may be nice to finish with more beach time rather than start.

I'm not overly interested in doing any time in Bangkok, as I just did a two week trip in Thailand recently and spent about 4 days in Bangkok, and I don't have any urge to return anytime soon. My current line of thought, is to fly into HCMC, head up through vietnam and to Hanoi, and then into Laos and back down towards cambodia...However, I haven't done enough research yet to know if this is really a good idea.

Sounds fantastic! I'd skip Northern Thailand this time around and just focus on taking your time through those three countries - though for visa consideration you may find yourself dipping into Thailand at some point anyway. With so much time keep the plan as a basic route and the timeframe flexible.