I have two pairs of Mojos and wear them for everything. They are the best all around active lifestyle shorts I have ever purchased. I like the fact that they do not have a liner (Breathe extra well when casual, but combo well with compression shorts for extreme activities).
6'4" 210 35" waist and I go with XL, but haven't ever tried L...
If you're on the fence, buy them. You shouldn't regret it.