You could give a variety of the $1 hand sanitizers from Bath and body Works. You could go as simple as just putting ribbons around the bottles in the wedding party color(s). If you want to do a little more, you could do a custom label for the bottle, or make a little gift tag, use decorative scissors to cut the edges, and print the couples name and wedding date on it, or some other appropriate message, and tie it on with the ribbons. I don't know anyone who wouldn't enjoy getting something like a hand sanitizer that they'll probably actually use, unlike many of the typical shower favors, that get tossed in the garbage as soon as people get home. Plus, Bath and Body works is everywhere, so you wouldn't have to order anything, since this is next week.
I know I'd like that favor!