I am familiar with Cartesian coordinates. I was also left speechless by "Stop Swimming."

And if you're avoiding pessimistic music, yeah, you can give Modest Mouse a miss. Raucous! Cynical. Occasionally real fuckin' dark. I keep starting to recommend parts of an album and then remembering the album is titled Good News For People Who Like Bad News.

In the vicinity, but much more nuanced and upbeat, there's Death Cab For Cutie... irony be damned. The lead singer was half of The Postal Service for their one album, of which "Such Great Heights" is unreservedly delightful and positive. Death Cab's discography proper is downright jaunty. The subject matter's just melancholy, at best.