one of the best investments i ever made, is the size large pack towel by MSR. the material is lightweight, thin and super absorbent. i always have it in my backpack, whether i'm trippin around for a day or taking off across the country. a towel can be used for warmth, as ground cover to stretch out on, and of course, to get you dry.
one night on a backpacking trip, i realized that i had forgotten to bring a sweater. my pack towel tied over my shoulders like a parka kept me warm, kept my arms free to work around camp, and continued to keep me warm through the night.
a perfect way to be inconspicuous about sleeping in public, is to stretch out on a towel on a beach or in a park. pick a nice shady spot, pull your cap over your face, and use your pack as a back rest or pillow and you're good to nap.
super absorbent pack towels can hold roughly 4 times their weight in water, which will prove useful when hit with sudden rainfall. find an overhang to hide under, a ledge, or set a tarp and wrap up with the towel. it will absorb the water off of you quickly, and help it evaporate from your skin as your body warms it up. also handy when using public restrooms to clean up, you can be assured that you have a means to get dry quick. the towel can be hung from the pack to dry while on the move.
the towel i used before the MSR was a freebie from a hostel in Vancouver. it was pink and purple flowers, oh so pretty.. haha. it's a must-have, no matter if you pay a good penny for it, or get one for free. for me, it's always worth the storage space.
an out stretched towel can be used when gathering branches and brush to get a fire started. a folded towel can be used as a pillow for sleeping, or for making your sitting spot more comfortable. i have used my pack towel to relieve my skin from sweaty pack straps rubbing during long hikes by draping it over my shoulders before lifting my pack back on. with so many uses there's no excuses to be without a towel. to call it crucial or creature comfort, that's for you to decide. for me, definitely a pack necessity.