I got a GPS for a tour, and quickly abandoned it for useful navigation in favor of paper maps. I haven't seen anything to change my mind for route finding.

One loaded with motels, restaurants, etc. could be useful. But my new favorite geek toy is a smart phone with GPS and google maps. It has all that, and freshly updated; it's lighter than my old GPS; finds my location quicker from a cold start; and I'm carrying it anyway. (Still worth carrying a decent point and shoot camera, though.)