Just a couple of questions - first, do most of you keep your passport with you or do you leave it at the hotel?
also, I am flying out of BKK, Chiang Mai and Siem Reap. Is an hour before the flight time soon enough to be at the airport? Don't want to spend all day there. thanks for all the great info

In Thailand, you're technically required to have your passport, or a copy, with you at all times. However, this law is never enforced. You will need your passport to cash travelers checks, if you're using them. Otherwise it isn't really necessary. I've had no problem leaving the passport at the hotel, but it is good practice to keep a copy of the picture pages with you, just in case.

As for airports, you should keep in mind that it can take anywhere from 20 minutes to four hours to get to the airport in Bangkok, and it isn't always predictable. Thai Airways requires you to check in at least 30 minutes before your flight. Most of the low cost carriers require at least 40 minutes. One hour for domestic flights is okay, but for international flights, give yourself two hours.

We always keep our passports in the room safe or hotel safe. We also have photocopies of our passports that we keep in another place just in case the real thing is ever lost or stolen...it's happened to me before and it's an unreal hassle to replace a passport with no form of ID, believe me.

For domestic flights within Thailand, an hour before is plenty of time...last trip we were at the airport only about 30 minutes before for flights on Thai Air BKK - CNX, CNX - HKT and HKT - BKK. For an international flight, like to REP, you'll need more time.

I took my passport on a hike once and sweated all the way through it making the ink from the visa stamps run through the pages. Before long the passport started to fall apart.

I usually feel comfortable leaving it in my room. If you are really worried you can usually leave them in a safe at reception.

http://www.travelsinasia.com

don't know how things will work at the new airport, but at the old one i always planned to be AT the airport 2 hours before international flights and 1.25 hours before domestic flights...

it takes quite a while to get to the gates at the old airport and traffic to the airport is unpredicatble...

i plan to use the same guidelines for the new airport

Been to Thailand twice and never had problems with leaving passport at hotel. Just as a security measure we digitally photograph our passports and email them to an email address we can access on our trip. This is in the event we lose everything. We do the same for tickets and vouchers. We also do photocopies but just in case it all goes this is our back up.