the Garmin GPSMAP 60CSX is on sale at Walmart. Its pretty much the apex of hand held maping GPS design (great satalite tracking, colour screen, waterproof etc). Yes the Colorado and Oregon from Garmin have touch screen and a bit bigger screens, but no real advantage tech wise. But you do pay a premium for those two improvements. My club runs alot of the 60 series Garmin units over the last 5 years with great success.
You can sometimes download topo and other maps from the net for different areas (for free), or you can buy the proprietory Garmin maps.
Only suggestion would be to buy (aside from the 12V power cord) a RAM mount for it to stick it to your cage or windshield.