I do lots of geocaching while out riding
I use a Garmin etrex vista hcx for both my route navigation and geocaching. I use the handlebar mount, though some say the vibration ruins the gps.
I've used this setup for years and not had a problem myself though. A pair of AA batteries last me a couple of days before they die while leaving the gps on constantly. If I turned it off on my stops it would last longer I'm sure.
I also have a power outlet cord I can use if my batteries die. You can see my gps/hat mount, but my gloves cover the location of my power outlet (cord not attached at the moment) located next to the right of my dash turn signal lights. (Bonus you get to see Georgie in the mirror)! Giggle