I've got an older Garmin eMap that works great for road trips, boating, and hunting (if I'm not in woods that are TOO thick). Surprisingly, Garmin has provided website-based upgrades and updated maps for a long time after they quit making & selling it. eMap is tough, accurate, and fun to use too. I'd recommend a remote antenna for increased accuracy. I took it on a couple of flights: one to Montana and one to UK. It was way cool to see the altitude and speeds as the flight progressed.
There are better units for sale today, I'm sure.