Here's a great way to plan your route or find out how far you have walked or biked.

You set up a recording session, trace your route on the Google map, and mark each leg with a flag. You can set it up for a there and back route with the distance and you can see mile marker flags. This method is much easier than driving your route. Probably more accurate also.

See the site at Gmaps Pedometer.

Here's a screen shot in Shoreline with a partially marked route:

Click on the map to enlarge it for viewing.