Thanks for everyone that replied! I knew I could count on all of you to point me in the right direction!

That said... I guess I won't be wearing a plaid to the benefit gala. It is a "Formal" event, and black-tie is specified on the invitation, but as most suggested, it's not my event, and it's definitely not white-tie formal. Most men there will be in tuxes, and women in gowns.

Some food for thought/conversation (not to start an argument):
If the PC/coatee is considered appropriate black-tie attire, and doublets are usually more for white-tie, then why do we see so many images of fly-plaids worn with PCs?