A lot of classical is in my bones, rather than things I regularly listen to. As a long-time choir singer, I've got a huge love of choral music (mainly English choral tradition and Renaissance Polyphony - Tallis, Palestrina, and so on). I went to a concert of Scandinavian and Eastern European choral music in the run up to Christmas, and was blown away by this:
which is Lithuanian, by Miškinis.
If I need to go to a happy place, though, and I often do, it's between the Bach G Major Cello Suite
and Electric Counterpoint
and frankly, that's where most of my interests lie: in the beginning, and at the end. I really wish I knew the early 20th century: I am not nearly familiar enough with Mahler, or with any of the Russians - Stravinsky in particular - but I'm working at it. It all neatly fits into all the other music I enjoy, though, so that's a start.