We went to Thailand for 2 weeks for $2000. It was 2006, so things might have changed a little. We did heaps - some beach lounging (including marriage proposal!) and some exploring, a cooking class, sunrise hikes, touristy stuff in Bangkok. We were without child then, obviously, so we could rough it a bit more, but it was easy to do. Where DH proposed was a beautiful family friendly fairly quiet island. Huge, plenty of tourist facilities, but not that wild vomit-in-the-gutter party type place that other islands are. Really nice.

I'd also rate Malaysia. A little bit more exxy, but so much easier to get around too.