These big colorful handkerchiefs are good for much more than blowing your nose. I always carry one in each pocket, and a spare or two in my pack. They work as pot holders, dishrags, washcloths, neckerchiefs, bandages, water prefilters, and any number of other things.
They are great as a head cover to avoid sunburn on the top of your head, or you can fashion it from under your cap as a cape to shade your neck and ears.
I prefer your basic blue and red, but they come in quite a variety of designer colors, so go ahead and live a little!