C is for Cash: When you're traveling from country to country, it can be difficult to keep track of all the different denominations. Thai bhat will be accepted in Thailand, of course, but also in some stores in Laos (as well as dollars, so make sure you bring a roll of singles with you). You'll need dong in Vietnam (the increments are confusingly large), but you should be able to get by with dollars again in Siem Reap. I had trouble using my credit card in both Luang Prabang and throughout Vietnam (even at larger shops), so it's good to have cash as backup—you'll probably need it.

F is for Flights: Bangkok's Suvarnabhumi Airport is one of Asia's biggest and busiest hubs, and there are plenty of ways to get there from the States. But only Thai Airlines flies direct from both New York City and Los Angeles. Flight 795 departs LAX at 11:10pm and arrives in Bangkok at 6:40am (on the return, Flight 794 departs Bangkok at 7:20 pm and lands in Los Angeles at 9:15pm). From New York, Flight 793 leaves JFK at 11:34am and arrives in Bangkok at 4:45pm; the return flight, 792, departs at 1:05am and lands in New York at 6:25am. There are also a number of flights with just one layover, in Tokyo. Here are some options:

FROM NEW YORK CITY
Option 1 (American Airlines):
American Airlines (AA) flight 167 departs New York City (JFK) at 11:30am and lands in Tokyo's Narita Airport (NRT) at 3:40pm the next day. This connects to Thai Airways flight 677, which departs at 5:15pm to arrive in Bangkok at 10:15pm. On the return leg, American Airlines flight 5835 leaves Bangkok at 8:15am to arrive in Tokyo at 4:00pm. From here, board American Airlines flight 168, which leaves Tokyo at 6:35pm to arrive in New York at 5:25pm the same day.

Option 2 (All Nippon Airways):
All Nippon Airways (ANA) flight 9 departs New York City (JFK) at 11:15am and lands in Tokyo (NRT) at 3:20pm the next day. From here, catch ANA flight 915, which departs Tokyo at 5:30pm to arrive in Bangkok at 10:50pm. On the return, take ANA flight 916, which departs Bangkok at 11:55pm to arrive in Tokyo at 7:35am the next morning. This connects to ANA flight 10, which leaves Tokyo at 11am to land in New York City the same day at 9:30am.

Option 3 (Japan Airlines):
Japan Airlines (JAL) flight 5 departs New York City (JFK) at 1:30pm and arrives in Tokyo (NRT) at 4:20pm the next day. At 6:50pm, JAL flight 707 departs Tokyo for Bangkok, where you'll land at 11:25pm. On the return, take JAL flight 708, which departs Bangkok at 8:10am and arrives in Tokyo at 4:15pm. Connect to JAL flight 8, which departs NRT at 7:35pm and arrives that same night at JFK at 7:05pm.

Option 4 (Continental):
Continental (CA) flight 9 departs Newark Airport (EWR) at 11:10 am and lands in Tokyo (NRT) at 1:55pm. This connects to Continental flight 6350, which departs NRT at 7:05pm and arrives in Bangkok at 11:59pm. The return flight, 6351, departs Bangkok at 6am and arrives in Tokyo at 2:30pm. Connect in Tokyo to Continental flight 8, which departs at 4:35pm and arrives in Newark at 4:30pm that day.