Asia - Chiang Mai to Siem Reap

Any advices for above. Prefer to fly direct but most flights are routed to BKK first. Exotic way , like a river boat cruise, would be be ideal if available. I have seen 7 days river cruise from Siem Reap to HoChiMin City on the Mekong and we are seriously considering that also.

Thank you.

Here's a recent article of someone's trip starting in Chiang Mai to Surin by bus, then on to the O'Smach boarding crossing into Cambodia and a hire car the remainder of the way to Siem Reap.

Looks like a backbreaking trip but if you're looking for a challenge...

http://www.talesofasia.com/rs-97-septrip.htm

Last year I flew non-stop RT from Chiang Mai to Siem Reap on Thai Airways, a prop plane ATR-72. Very easy, safe, fun and not expensive. There is no need to backtrack to BKK.