I've always quite liked http://cycle.travel - UK oriented but the map interface is OpenStreetMap based so can handle overseas as well. Website not an app, but may still be useful.
It defaults to offlow-maintraffic-roadroads (calculated from known traffic data, not simply road classification) and includes a very useful height mapper display, so you can tweak a proposed route to avoid steep hills.
It also offers randomly generated "short tours" - given a defined start point and distance, it will try to come up with possible cycle routes in the local area. For example, "twenty miles round trip to something near Cambridge", or "a hotel fifty miles from Leeds with a route there and back". Quite a clever idea, IMO, though I've not tested any of them out...