Something I've wanted to do ever since visiting Bariloche is take the "Lake Crossing" between Bariloche and Puerto Varas. You might look into that. The mountains and scenery in that region are spectacular.
A longer trip, but you could bus from SCL to Mendoza, then take the overnight bus to Bariloche, then the Lake Crossing.
(Hmmm...
I may have to look into some tickets...)