We use Mapsource and Topo USA. We can plot a route on the computer and it tells you mileage and then you can also look at elevation profiles. The maps can be downloaded to the GPS. We use the Etrex by Garmin. Its kind of a neat little tool. Especially around here where half the roads aren't marked and there are some nasty climbs. Also if one of us is out alone the other one at home has a map of the route in case of emergency.