I am just talking about a regular letter with paid airmail. I don't think it would make any difference if it was certified or registered though. I figure to expect about TWO WEEKS, does that sound right to you?

I'd say two weeks from a major Thai city. CM, Pats, Phuket, Bangkok

Double that, or more, from the sticks.

I regularly get mail (that which actually arrives) from the US with postmarks from Udon Thani dated two weeks previous.

Mine has usually run between 10-14 days.

When I lived in Atlanta, mail from here (Bangkok) took around 3 weeks to arrive on average. To LA, it took around 2 weeks. No idea why the discrepancy. I guess a local i.e. US mail issue. Letters to London generally take 5-7 days.

Edit for clarity

My post normaly takes a week to the US, but can take 3 weeks sometimes to my friend in Oklahoma, i don't know why....