I have had these Keen Commuter Sandals for 2 years now and used them in the summer commuting. I posted a review last year here: http://robonza.blogspot.com/2010/11/review-keen-commuter-sandals.html.
I have always really liked them, but when returning them to their ancestral home- the beach, they really shined.
If you ever find yourself looking for another reason to pick up a pair of Keen Commutr SPD Compatible Sandals, riding on the beach is another reason!