People have gone to a lot of trouble to create scenic areas in SL. It will take a long time to see anywhere near all of them, but so far Riverwalk is among my favorites.
OK...I admit it. this is just an excuse to post this cropped image from a snapshot I took there, for lack of a better place to put it, so I can have it available for my profile. Riverwalk really is gorgeous, though; visit it when you can.