Thanx to all. I'm based in Guam, so nominally US (though try convincing the mainland about that!). Anyway, taxes proved too prohibitive to do the Bangkok Airways pass. Also, timing was a little poor. So others can better plan, there will be a nonstop Luang Prabang to Siem Reap on Siem Reap Airways starting Nov 1, 3 times a week (I forget which). So, only 1 $80 coupon plus taxes, which amounted to about $25+ per segment (Luang Prabang has higher taxes than Siem Reap).

So, our final itinerary, which we are currently on, was mostly overland. BKK 4 days then Siem Reap 5 days (really only 3 full days because 2 full days lost to overland transit by bus...btw, non-existent roads on 90+ % of Cambodia from Poi Pet to Siem Reap, so verrry bumpy and long rides; also, if going overland, don't book roundtrip bus tix. It's a scam. No bus to pick you up. Turns out the Thai travel agents book the trips but keep all the money, so the Cambodian side has to make money by driving real slow and taking a longer route so that guests arrive really late at a contracted guesthouse, which pays the bus about $7 per head in the vans (not large buses)...nobody to take you the reverse route...just book in Siem Reap about $12 bus all the way to Bangkok).

Anyway, after Siem Reap, train to Suratthani, then boat to Koh Samui. We are on Samui now, will leave Sunday and do the train in reverse, then a couple days in Bangkok again.

For 2 people, adding Luang Prabang was looking at around $700 for the flights and visas alone, so we pulled that locale, as well as Chiang Mai. Wish we'd just stayed in Siem Reap longer instead of Samui, but each their own.

Sincere thanks again to all. I'll use the Bangkok Airways pass in the future after a direct flight between Luang Prabang and Siem Reap is installed. Then I'll report on that experience. A direct flight would truly make that routing a bargain at $80 + taxes.