The search for a "perfect" pair of weekend shorts starts with a 9 inch inseam. I think a longer length is too formal, and anything shorter looks junior. (Although a quick look at pictures of Hollywood celebrities over 40 shows me that anyone who is a size two can wear any length they want!)
This pair from J. Crew is cut a little lower (I'm a big fan of a mid rise in jeans, but strangely enough, a mid rise in shorts looks matronly) and also comes in a variety of colors:
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I think your point about the proper 'rise' in shorts is right on.