I wear contacts. I bought a couple pairs of the winchester clear shooting glasses at wal mart. That way I can replace mine if i scratch them up too bad or if I need to loan out a pair. I prefer the clear lenses to yellow, but that's just me. If it's excessively bright or I'm at another range (not my "home" range) that doesn't offer the shade mine does, I'll wear my Ray-Ban aviators. Yes, the reflective kind. Like the terminator.
I'll be back.
EDIT: Your contacts probably won't feel comfortable for more than a few hours the first few days. I've been wearing contacts for 9 years. I wear Acuvue 2s. If your eye doctor hasn't recommended any length of time to wear them for the first few days, try this:
The first day, wear them for 2 hours. For every day after this, add 2 hours. Your contacts will get a protein build up and become blurry when they've been on for too long. They also might feel like they are drying out. If you feel any of this, go ahead and take them out. Your eyes will adjust to them and pretty soon you'll forget you even wear contacts until it's time to take them out or put them back in.