I've had a number of epiphanies over the past nearly three years of this -- beyond the obvious cost differences. Here are a few of them that seem to resonate with people:

• It's amazing how little wear and tear these things show when you have more than one pair.
• Prescription sunglasses? I can see outside in the summer -- without squinting! THIS is what the beach is like?
• The frame's nooks and crannies stay very clean when you're not wearing the same pair each day.
• I play (more) with the kids knowing that if my glasses get broken, I've got another pair to replace them.
• It's really nice to be able to afford multiple pairs of glasses for specific purposes/settings rather than needing one pair to look nice and perform in all situations.