Originally Posted by Lazors

Tchaikovsky is a good start. I never got hooked on his stuff. The violin concerto is kinda dull to me, which might be weird for a violinist to say. That cadenza was amazing though.
That said, you might want to try Shostakovich or Rachmaninoff for russian harmony. I'm not super into orchestral music myself, but i like Sibelius and Stenhammar a lot.
If you want to get into more modern stuff, Olivier Messiaen, Toru Takemitsu and Rautavaara are pretty much my favorite composers atm.