Overland in Asia is the way to go. Direct flights, especially to/from Cambodia can be pricey.

Check out http://www.travelfish.org/ for lots of great backpacking info/downloadable guides. I personally wouldn't use your Hilton points in Asia (with the exceptions of Hong Kong and Singapore, or maybe some resorts). Clean, decent accommodations are available for $30 or less per night in most areas.

Ah, but you may have missed out on this OP's previous thread on this forum, which asked about overland. Apparently not his cup of tea.
http://www.flyertalk.com/forum/asia/...anoi-land.html

But your suggestion of travelfish.org is a good one for FT'ers reading this, who might be interested in other useful sources for overlanding this region. Likewise your advice not to get stuck on using points in the big intl hotels. At least if one is interested in saving money.

I just returned from there, and we did over land from Bangkok to Siem Reap. We paid about $25USD for a nice hotel room with breakfast included in Siem Reap, and we didn't fly back because it was so expensive. Getting from Siem Reap to Bangkok takes a full day, but if you are short of cash its worth it. We paid $25USD for a taxi from Siem Reap to the border, leaving at 7:30am. Once there, we waited in line nearly 2 hours just to get through customs. They had 2 agents working for non-Thai passports, and who knows what they were doing but we didn't move for over an hour. That was the most frustrating part of the day. If you time it to get there when the border opens, you most likely would avoid that wait time.
Once on the other side, we took a tuk-tuk to the bus station, which was about $1/$2. Bus to Bangkok was less than $10, I think it was $8. We arrived in Bangkok early evening, around sunset. From there we took a night bus down south.... long travel day but much much cheaper than a flight would have cost.