I know the US passport card is technically only valid for travel to Canada and Mexico. But for practical purposes, is the passport card any better than a US driver's license in Thailand?

PS: I already have a current and valid passport book, I'm only interested in the card for regular everyday purposes, and also as a strong second form of ID.

take a copy of the first page, your stamp and arrival card. leave it (passport) at the hotel.

Not sure what use a passport card would be in Thailand. Can't use it as a drivers license, can't use it to get on an international flight, can't use it to re-enter the USA from Thailand.

On the flipside, it can be stolen with your wallet and resold to someone in the Americas for nefarious purposes.

Like BKKJames says, copy your passport pages and keep them with you for everyday uses, along with your valid US driver's license if you plan to drive. Leave your passport in a secure location to make it harder to steal.

Then take normal precautions to safeguard your wallet like you would in any tourist area that attracts those who prey on tourists.

From the banking thread I can tell that it's getting harder and harder for ex-pats to open bank accounts and do other similar tasks in Thailand. That's the real reason I'm considering getting a passport card before I come over – just in case the regulations get even tighter, and a passport plus drivers license isn't enough to open a bank account or do something else.