I'm generally an 8.5 but went with the 9.  The 9 fit great.

It was a little tight around the front of the ankle area but just needed to be broken in.  After a few days, they feel great.  I found them to be super comfortable.  I just went on vacation where I had to walk a whole lot in the sun and heat, and they always felt comfy.  I'm very happy and may even get another pair.