Thanks to everyone who responded to my original posting back in October.   We are now poised to begin our trip (leaving Jan  26) and would welcome additional suggestions/advice.  

For better or worse, we have abandoned the idea of basing ourselves in Bangkok;  instead, we're flying in and out of BKK but planning a more or less "play it by ear" 6-week swing hitting parts of Cambodia, Vietnam and Laos.  Only confirmed bookings so far are for the first four nights in Bangkok (Majestic Grande hotel) and then Air Asia flight to Pnomh Penh (no hotel yet).   Idea from there is to explore PP, check out Sihanoukville and Siem Reap in whatever order makes sense, and then move on to Vietnam (presumably flying directly to Hanoi).  Based on comments on this forum, would plan on spending time in Vietnam in and around Hanoi, and then move on to Laos (Vientiane and Luang Prabang) before heading back to BKK.

Questions:
-   How does the above itinerary/flow of travel generally sound?
-   Underlying assumption here is that it should be reasonably easy to figure this all out as we go, planning each leg of travel a few days in advance, recognizing that we will need to be flexible on precise timing and, for flights, might not find bargains. Is this assumption generally correct?
-  Is skipping HCMC a mistake?  

Thanks again.   

I like playing it by ear! Of your destinations, I've only been to Thailand (and I've stayed at Majestic Grande), but I do like the idea of planning a little bit at a time, as you go!

Let us know how it all works out.

Yes, it should be easy to figure out as you go. Most of the people here much prefer Hanoi to HCMA, but there are other who love HCMC. But you only have 6 weeks, so you have to cut some destinations.

Especially with Air Asia, the closer you get to the flight date, the more expensive the flight will be. So if you were planning to fly Air Asia because it's cheap, check other airlines as well, as the full service airlines are likely to be less if you are just a few days out from your flight and especially, if you need extra baggage allowance or other things that Air Asia charges extra for.

Also, hotels are less expensive from booking services. SHowing up and trying to negotiate a price will mean you pay more than if you get on your laptop and reserve a room the day before from one of the booking services. In Thailand, www.sawwasdee.com elsewhere www.agoda.com www.asiarooms.com Also check out www.latestays.com as you can sometimes find some real deals for places in the next week or so.

If you don't have guidebooks for each of these countries, pick them up in Bangkok at Asia Books.


Enjoy!

I totally agree about booking your hotels ahead of time (even if only the day before) and doing it on line. I book directly with hotels and usually pay less than the rack rate that I'd pay if I just 'walked in' wanting a room.

Have returned from this trip and wanted to circle back and thank everyone who offered advice as it was being planned.  The  reason I'm not posting a proper trip report is because I was compelled to return home three weeks early to deal with a temporary hip injury -- slipped on ice two days before departure! -- that made walking virtually impossible and thus necessitated major last-minute shifts in the trip style and itinerary. Instead of a rambling, rolling adventure, the trip turned into a very limited and limping view of just a few places:  most of the time was spent sitting around in Phnom Penh (at the Plantation Hotel, which is not a bad place if you have to sit around) but also got glimpses of Kampot, Vientiane and Luang Prabang.  Each of these destinations seemed wonderful and cried for further exploration.  Except for Sorya bus to and from PP to Kampot we flew from place to place, necessarily missing much (notably Siem Reap/Angkor) but making for easier (if not cheaper!) travel. Compared with India, travel logistics were a breeze; it was easy to arrange transportation and hotels on the go. Now, with mobility essentially restored, my interest is in planning a return trip to this part of the world and seeing everything I missed.  Thanks again.

brk01, thank you for touching base with this forum. So so sorry to hear (read) about your hip injury and how it caused your trip to be cut short. I am happy that you plan to return to S E Asia! It is such a wonderful destination.