I like all these responses. Bicyclists are so much a varied lot of people! In my original post I said that I'm just as comfortable in street clothing as in cycling shorts, but my wife theorizes that I may have been wearing the wrong size and/or brand of shorts. Also, I don't notice any difference in efficiency between when I used SPDs and now that I'm just using just platform pedals - I'm thinking it's because I may have never learned to spin in the SPDs correctly. If I go back to SPDs (they're still in my closet) and spend some time learning how to use them correctly it might be a good idea. I do like the security of being "attached" to the bike.