I posted this same question not too long ago:

http://forums.teamestrogen.com/showt...ghlight=undies

Since I posted it, I've done it both ways and I honestly think it's fine either way depending on the shorts. I have one pair of shorts that bug me w/o undies. A few other pairs that are more comfy without. And a couple pairs that I don't care. I wear seamless panties when i wear them w/ bike shorts.

Today I wore regular ol' pants (no chamois) and undies for a few miles to test out a new sadddle. Felt totally fine.