In the last year I've become a pretty huge fan of Levi's, particularly for their commuter line of pants and shorts. I have 510s, 511s and 504s, and it's nice that the short version fits consistent with the pants version in terms of slim, relaxed, etc.
Last summer the 511 commuters were one of my most commonly worn shorts, but somehow my thighs grew over the winter (maybe it's whiskey weight?) and they're pretty tight. After having good luck with the 504 jeans, I decided to try these shorts. More relaxed than the 511s, but similar in most other ways, they're going to be my new favorite shorts for the summer. The material is stretchy enough, and they're fitted but not tight. I'm short (5'6"), so I avoid rolling down the bottom hem (meaning, I wear them as pictured with the bottom hem rolled up an inch) and the outseam length is perfect. They have a hidden stash pocket on the right thigh, seam (look closely in the image and you can see the zipper pull). It's a surprisingly sufficient pocket that could hold your ID, cards, and other tiny valuables.
OH! And my other favorite part about these is the availbaility in a 31" waist. 30 is too tight, 32 is baggy on me so I take advantage of the ever-elusive 31" whenever possible.
If you know of any other similar fitting shorts in a 31", add a comment!