I usually memorize as much of the route as I can, be it single day or multi-day ride, and use an Android phone with the Locus Maps app and offline maps to double check at intersections that I'm not sure about. I've been using this set-up for the past year, and I can't see it changing any time soon. I have vector maps for on-road use, satellite maps for off-road and looking ahead for suitable camping sites, and terrain maps for a rough idea of the climbs ahead. It works so well that I rarely turn on the GPS receiver, so I can pinpoint my location the old fashioned way, by looking at the map and correlating it with my surroundings.