I use a Garmin Edge 800, still available on Ebay. It does turn-by-turn directions from a TCX file which RidewithGPS will produce for your route. The map feature is a good thing to have. I never let it pick the route, rather I plan my route beforehand and load it into the device. We did a 400 mile solo tandem tour in the Czech Republic with over 600 turns and had no paper maps at all. Worked great. The current comparable unit is the Edge 1000 or the Explore 1000, slightly larger and more expensive units, though larger would be good. Unlike a phone, these units are all waterproof and work with gloves on.

After using my Garmin, trying to tour unknown territory with paper maps would drive me nuts, particularly since I try to never ride on main roads. With the Garmin, I just turn the pedals and go where it tells me to go.