I'm a 32" (maybe very slightly less) waist and went for size 30. They do shrink quite a lot after an initial soak but only very slightly in the waist in my experience. The width on the leg after a soak is slim but not too slim, which is exactly what I was after. There's a nice heavy weight to the cloth. I'd say sizing down by two would be the way to go in most cases.
I can get a fit pic later on if it would be helpful?