I've found bikehike to be very good.
You can't save routes online, by you can save them to your hard drive and email them.
Yup. BikeHike.
But some words of warning.
BikeHike will allow you to limit the number of Waypoints on the route. 249 if your GPS has a 250 per route limit.
When you do this, BikeHike chooses the locations and draws a straight line between each point. This results in the distance and climbing being incorrect. Shorter distance and the summits of short hills being missed.
To plan AUK rides, allow BikeHike to use maximum points so the route is as detailed as it can be, so the distance and climbing are closer to reality.
On BikeHike, I create a GPX route with max points, then import it into MS Autoroute or Tyre toTravel to trim for my SatNav.