Okay so HERE IS A GREAT IDEA that if it doesn't already exist, I expect will exist within the next 5 years or so.
There's two ingredients: first off, is GPS software!
Right now most GPS software offers you two choices when going from A to B: shortest distance or fastest time. They do this giving each section of road two scores: a distance score (how long you go along road X) and a speed score (how fast road X will take you: is the speed limit 40? 80?). Fancier ones use real-time traffic information to tell you how fast traffic on the road is actually moving, so you have a better speed score.
The second ingredient is photos: specifically, geotagging photos. Right now Google uses some geotagged photos to give you shots of things nearby on Google maps, since the geotag stores where on the planet the photo was taken. The problem is a lot of this tagging is done by hand. Once everyone starts buying cameras with GPSs in them, you get geotagging for free, and the number of geotagged photos will explode!
All you need to do is put these together and you've got a third score you can now add to roads: "number of photos taken on or near this road" - in other words, "scenicness". You'll be able to say "I want to go from here to school, and I want the scenic route!" and your GPS will say "How much are you willing to be delayed for some pretty scenery?" and you'll say "Oh, 10 minutes", and hey presto, an alternate route to your destination that gives you some more interesting views than you might get otherwise.
There's some wrinkles: you'd need to do some smoothing to filter out shots of accidents from the day before, say, and also filter out people who might try to grief the system, but it'll work pretty well right out of the box. Add on some content analysis (tags, say) and you might even be able to figure out what pretty scenery you should be looking for at each point, and even filter by them. It would probably work better in the country than in the city (where things like "Michael Jackson's House" will be covered in photos), but it'll still be pretty neat.
Anyway it's a pretty obvious idea but I wanted it out there in case someone tried to patent it, if they haven't already. GOOGLE/GARMIN GET ON THIS PLEASE, I WOULD LIKE TO USE THIS FEATURE