Have you tried printing out the google map?

Most (bike-portable) GPS units will do a route. You'll have to generate this externally, on a computer, and download it to the GPS. The DeLorme units are pretty good at telling you roughly where to turn; unfortunately, you have a choice of staring at the GPS or checking it to find you should have turned a quarter mile back.

My personal opinion is that GPS for a bike in 2011 is like a laser in 1969 -- it's a solution looking for a problem. I'll give a minor exemption to the Garmin unit (705?) with a restaurant and hotel lookup function -- good for a touring cyclist with a cell phone to find a bed in the east.