Olafur Arnalds, particularly the songs "30:55" and "33:26"
It's kind of post-rock-y. Or like, "modern classical" I guess. The former song has some really nice piano, and the latter song has some reaaally nice strings.
I grabbed this album (Eulogy for Evolution) on recommendation for good, ambient "work music" but it's starting to become too distracting because it's too good, haha.
Last.fm's similar artists include Balmorhea and Sigur Ros. In my opinion, it's not very similar (closer to Balmorhea than Sigur Ros, though it's still a stretch), but if you particularly like those bands, then this is worth checking out, imo.