With progs like "Hike" and "Maemo Mapper", tablets are hard to beat. The Nokia GPS puck is amazingly sensitive. Hike is cool. Take a pix of the park map. Calibrate it with 3 points to fit the GPS fix on the picture and it puts you right on the trails IF the map is right...some aren't.

Flying's better, too, but don't let the pilots see it. I had the GPS puck in the window, Maemo Mapper running with STORED (no cell or wifi avail) tiles from Runway Finder of the aeronautical charts for the trip on the internal 16GB SDHC. My seat mate, humorously an iPhoner, and I were tracking our flight on the very chart the pilot should be using when the copilot came back for some reason. On his way back to the cockpit, he spied my chart! I'd rather he flew in his seat, but he said my GPS worked as good or better than the one in the 727!...