Assuming you have an Edge 205, 305, 500, 605, 705, etc. and you are looking for bike routes (rather than just base maps), you will find lots of options on connect.garmin.com, although the search feature is somewhat weak.
This is easy, and works great: see my previous post on installing pre-made free Open Street Maps.
The maps are very nice and complete. They are great for following uploaded .tcx Course files. But they don't work very well with .gpx Route files, although other users have had similar trouble with Garmin maps. I've never used the pay Garmin maps.
For easy course file creation, I use ridewithgps.com, draw a route, save it with a name, and Export it as a .tcx file.
Thanks rm! (My fingers won't let me type your full username. Ha.)
That's funny, I know what you mean!
I'll mention MyTourBook for storing uploaded ride .tcx recordings.
It's free and open source, and runs on your local computer, not on a web site.
I can get daily, monthly and yearly ride totals, distance, average speed, total elevation, etc.
The maps can display the route colored by the speed at each point.
It has zoomable graphs of elevation, speed, heart rate, feet/hour climbing, etc.
It took me a while to get it set up the way I like, but now it's easy to work with.