Originally Posted by Pwdrhnd
When you get old and out of shape you don't want to scare too many people by wearing only bike shorts. I now wear regular shorts over my bike shorts.
Quite a few folks I ride with regularly are pushing 60 and are still quite cut and trim in full lycra bike kit. So I figure that, so long as I keep enjoying riding the way I do (read: too much, too fast and too long for most folks' comfort), and keep eating right and doing other things (namely skiing, but other stuff, too), I won't feel embarrassed wearing the lycra into my older days.
Then again, your own mileage may vary. Wear whatever is functional and comfortable - both from a literal and emotionally practical standpoint.
JamesJ: if your commute isn't longer than a couple of miles, I wouldn't get too worried about changing into bike kit for the commute. I have a 2-mile daily commute in DC and don't wear full kit, though I'll take a change of clothes during the "HHH" weather days. However, if you are developing some discomfort in the nether regions, perhaps a pair of cycling liner shorts (lighter weight lycra-blend shorts with passed chamois) would be an ideal base layer for commuting. You'll also want to look at your bike's setup, because I'm guessing that you might not have the best comfort-oriented position on your ride.