That is a very broad area, but may I suggest Sibelius & Mahler's symphonies, and Rachmaninoff's Isle of the Dead and Symphonic Dances for starters.
I'll second these suggestions. Try Mahler's 6th symphony, the Rachmaninov mentioned above, Shostakovich's 5th/10th symphonies, etc... those are the recommendations I shall come up with for now.
By the way, nesf, do you know Prokofiev's Romeo and Juliet? This is an absolutely amazing piece, one of my favourites. The 'Juliet's Death' finale I think is one of the most beautiful pieces ever written. Makes me cry every time I hear it... and the ballet also contains some of the most jolly music, such as the 'Morning Dance'.