My suggestion is to check your bags through to final destination and then take a clean change of clo

Is it the Novatel that is across the parking lot? Or do either Bangkok or Star alliance have an all night lounge? If I take the early flight it would only be a five hour layover. I'll have had plenty of sleep on the planes, and I can sleep anywhere as long as it's safe!
I believe the Star Alliance lounges are not 24 hours. At least that was my experience several years ago. There are dayrooms lastminute airplane tickets you can rent by the hour... the name is odd, something like Louis Tavern... I'm sure it is listed on the airport lastminute airplane tickets website
lastminute airplane tickets Any chance of checking lastminute airplane tickets your stuff through to Cambodia from home? All of the Thai lounges are closed from 2-5 am. The Louis Tavern, which would probably be a very good option is on the air side so you can't go through immigration and pick up your luggage. We've stayed at the Novotel - there is a shuttle that takes 5-10 minutes. It's an okay hotel.
lastminute airplane tickets Craig is right on about the lounges not being open 24 hours. When I fly the 6:05am NRT flight, I have to go to the Louis Tavern lastminute airplane tickets the Craig mentioned. It's OK, but not nearly so nice as the Thai lounge(s).
4th floor transit area at the airport have nice comfy reclining "couches" that work well for a longer layover. I have spent 4+ hours there many times. They also have very clean FREE showers on the 4th floor. Lots of people hang at the airport over night...so you would have plenty of company. They also have a transit hotel that you can book --by the hour, I think.....
My suggestion is to check your bags through to final destination and then take a clean change of clothing. If you want to use the showers, also pack a small towel and soap/shampoo. They do have a towel/shampoo/soap pack available for $6. If you want to exit the airport for a hotel, I believe you can get a "pass" that allows you to leave the airport and then re-enter easily. Be sure to tell them before you leave the customs area. Otherwise, follow the transit signs when you arrive and find a comfy place to hang out.
Whoops... I made a comment on this thread earlier and really was commenting about ICN (Seoul) airport and not Bangkok. As I wrote the comment above, I was sitting in Seoul--somewhat jet-lagged and my brain was not running on a full tank. Must have been all the spicy kimchi I had eaten over the past month or so!!