I will say it again: in places that are dimly lit or where you would have to wait for change always pay correct amount. At 7-Eleven counter and similar pay with 1000 THB notes.[/QUOTE]
You are so damn right.
When in Thailand I try to change as much 1000 notes in shops like 7-Eleven or restaurants. Then tend to collect loads of 100 notes of which I will use in bars and clubs etc.
So whatever I buy in 7-Eleven, I always pay with a 1000 THB note. They have loads and dont mind. This works well for me. When in the bars and restaurants my friends are surprised by the amount of small notes I have in my wallet and beg me to change some of their larger notes, so they can pay their bill.