I will mention that I have only worn these shoes one night so far, but I was on concrete for about 5 hours.  I wore these w/ dress pants and thin trouser socks.  These look very nice and seem well made.  I have other Clark shoes and wear the heck out of them, so I'm familiar with the brand.  These do NOT feel like your wearing heels at all....more like boots maybe.  I love that about them.
They are pretty snug for me and I ordered the same size I would for a pair of tennis shoes (8.5) thinking I might wear them w/ thicker tights at times.  Normally on dress shoes I can wear an 8 or even a 7.5....but with these I would order your regular size.  I thought maybe I should have gotten a half size larger, but the back of the shoes does seem to be a tiny bit loose, so I'm sure that it would be worse with a bigger size.
My daughter wears a 7.5 and even she said they seemed snug around the top of your foot.  I ended up loosening the top strap (near the toe) and that helped a tiny bit but doesn't look as nice, so hopefully they will loosen up the more I wear them.