p3 - I see that you and I posted at the same time. If you look at the link that KimJapan provided, it shows that Bangkok Airways has through-check relationships with both Thai and Lufthansa. You should present your separate BKK-REP ticket at check-in so that your bags can be checked through. You will still have to obtain BKK-REP boarding pass in Bangkok - there are special transit check-in counters to do this. They are on the second floor which is the same as your arrival floor. You then pass through screening for transiting passengers and proceed to your gate.

You don't go through immigration in Bangkok when in-transit to another country. So if your bags are checked through to Siem Reap, which they will be if you're on the flights that gearsau pointed out (don't know why you won't tell us what airline you fly out on) then you'll go through immigration in Cambodia.

It doesn't matter that your tickets to Siem Reap are a different set of tickets. You can still check your bags through from Boston to Siem Reap. Just present all of your tickets when you check in at Boston. Tell them you want your bags checked through to Siem Reap and make sure your baggage tag says REP. Then you do not go through immigration (as per Craig's instructions).

The airline you'll be on when you arrive at BKK is Thai (filmwill, p3 did give us the info above: Lufthansa/Thai), I do know that they will transfer bags to Bangkok Air.

While the page Kim links to is useful, it tells us which airlines Bangkok AIr will transfer baggage to as you are leaving Thailand, flying on Bangkok AIr to BKK and then onward internationally on another airline.

Sorry--missed that. Craig's right. I'm not reading all the posts! :P

Kathie is right I cannot tell you the number of times I have checked in with tickets to my final destination that were not ticketed together & have no problems checking bags all the way through. As long as they have that baggage agreement though!!!!
I would still be inclined to go for the later flight though just in case you have delays leaving the east coast or germany. Sounds like you are leaning that way anyway. Have a fantastic trip.

I think with your flight to Bangkok coming from Germany rather than some place in Asia in January, there could be weather issues. So I, along with the others would suggest doing the later flight. Who knows, once you get there, maybe you can hop on the earlier one if it isn't already full? Ask when you get your boarding pass at BKK.

Oo my gosh, you guys are so awesome...I know I could count on you guys for the answer/advise! Thank you so much for the replies.
It's good to know that we can request the bags to be checked thru all the way to SR! :-)

I will book the 11 am flight just to be safe...thanks again!