I stopped carrying a backpack this summer. Now, I usually geocache with my Scottevest Travel Vest. It so much lighter to carry and I don't worry about setting it down and forgetting about it.
It fits so much more than what I put in it:
pencil
swag
tweezers
flashlight or headlamp (although that goes on my head)
small hand mirror
my leatherman utility tool
small first aid kit
GPS
camera
cell phone
gloves
plastic baggies
water
Happy Caching.