Some ideas:
Beethoven 5th and 9th symphonies
Mahler 2nd symphony
Stravinsky The Firebird
Shostakovich 5th symphony
Bernstein Prelude, fugue and riffs
Wagner Overture Die Meistersingern von Nuernberg
Verdi requiem
But don't bother unless you are prepared to invest some hours of concentration. If you want wallpaper tune into Classic FM.
If you get to like a work and want to get to know it properly, buy the score and follow it while you listen. It can be hard graft but you reap the rewards in connecting with the music.