One addition to 'B' composers: Bruckner - his music can sound very boring or just awesome - depending on day at least to me. Some of his choral works are simply amazing.
And couple of additions to 'S' composers: Sibelius, (not only because he is Finnish ) His violin concerto is one of the most beautiful pieces of music ever written. And tricky one to play...Oistrakh's version is old but still one of the best versions I've heard. And his symphonies are quite interesting - mainly because his music evolved during the years to very interesting directions.
And then there is Shostakovich - maybe the most underrated great composer of the last century. Some people think that his quite modern music is monotonous, dark and too 'heavy metal' for their ears. But Shostakovich had a great sense of irony and he had also lyrical, lighter side in his music. Like the slow movement of his 1st piano concerto - very touching and beautiful indeed. He also wrote very much music for films.
I got to hear one of my favourite pieces of music again today when the radio played Richard Wagner's " Ride Of The Valkyries ". It is such a descriptive composition, in one's mind one can see the Valkyries riding along in slow motion gathering up the Souls of the fallen warriors ( quite stirring ).