Classical symphonies: Mozart - both g minor symphonies, Beethoven's 3rd
Romantic symphonies: Schubert's unfinished, Tchaikovsky's 4th, 5th and 6th, Mahler's 4th, Maadetoja's 2nd
Modern symphonies: Prokofiev's 1st, Shostakovich's 1st and 5th, Rautavaara's 3rd, 5th (especially recommended!) and 7th, Duttileux's 1st and 2nd
Slovenian symphonies: Skerjanc's 4th and 5th - this one is on youtube, Skerl's 4th
Tone poems: R. Strauss - undisputed master
Operas: Verdi, Puccini, R. Strauss's Rosenkavalier, Sallinen, Golob, Kozina (Equinox)
Piano Concertos: Rachmaninov's 2nd (I dislike the 3rd though), Rautavaara's 1st, Prokofiev's 2nd
Violin Concertos: Mendelssohn, Tchaikovsky, Khachaturian, Prokofiev's 1st, Rautavaara
Clarinet Concertos: Mozart, Weber, Lindberg
Cello Concertos: Dvořak, Shostakovich's 1st, Rautavaara, Kokkonen, Golob
String quartets: Beethoven (undisputed master), Grieg, Bartok, Shostakovich, Sallinen's 3rd
Piano sonatas: Beethoven, Skrjabin, Prokofiev
I would write more, but my daughters are awake, I just don't have time now. ;)