I was sorting out the converting of mapping from Google Maps routes into my Garmin, which is a fecking nightmare to get to work properly. It isn't as straight foreword as they try to tell you, the new Garmin Basecamp software has to be the biggest pile of s!$%e I've ever used, it brings numerous errors into the routes (like randomly changing destination points ), anyway it's sussed now using Mapsource and a rather neat converter from KML (Google) to GPX (Garmin) format which can be loaded on to the satnav.
It depends what you want to do with it. I'm putting in a detailed route though France to Spain and back that covers a 9 day bike trip I'm taking in mid May, it's probably the best tool for the job, there just isn't a simple way to do it from the PC (dispite what they tell you). You could just put in the co ordinates of each B&B / Hotel and do 'place to place' that would simplify it, but if you want to take a certain route it gets a whole lot more complicated (there are restrictions on Waypoints etc)