Here's a small list to get you started. I recommend you just go with what you are instantly drawn to at first and then branch out from there. If you like Romantic music you MUST indulge in the symphonies of Brahms, Dvorak, Beethoven, Mahler, Tchaikovsky and Sibelius: they will be your bread and butter, your best friends, you are the peanut butter, they are the jelly...
1. Symphony No. 9 in D minor "Choral" – Ludwig Van Beethoven
2. Symphony No. 5 in C minor – Ludwig Van Beethoven
3. Symphony No. 3 in E flat major "Eroica" – Ludwig Van Beethoven
4. Symphony No. 6 in B minor "Pathetique" – Peter Ilyitch Tchaikovsky
5. Symphony No. 41 in C major "Jupiter" – Wolfgang Amadeus Mozart
6. Symphony No. 9 in E minor "From The New World" – Antonin Dvorak
7. Symphony No. 6 in F major "Pastorale" – Ludwig Van Beethoven
8. Symphony No. 40 in G minor – Wolfgang Amadeus Mozart
9. Symphony No. 4 in E minor – Johannes Brahms
10. Symphony No. 9 in C major "The Great" – Franz Schubert
11. Symphonie Fantastique – Hector Berlioz
12. Symphony No. 8 in B minor "Unfinished" – Franz Schubert
13. Symphony No. 5 in C sharp minor – Gustav Mahler
14. Symphony No. 2 in D major – Jean Sibelius
15. Symphony No. 7 in A major – Ludwig Van Beethoven
16. Symphony No. 2 in C minor "Resurrection" – Gustav Mahler
17. Symphony No. 10 in E minor – Dmitri Shostakovich
18. Symphony No. 5 in D minor – Dmitri Shostakovich
19. Symphony No. 3 in F major – Johannes Brahms
20. Symphony No. 39 in E flat major – Wolfgang Amadeus Mozart
21. Symphony No. 7 in E major "Lyric" – Anton Bruckner
22. Symphony No. 4 in F minor – Peter Ilyitch Tchaikovsky
23. Symphony No. 1 in C minor – Johannes Brahms
24. Symphony No. 9 in D major – Gustav Mahler
25. Symphony No. 4 in E flat major "Romantic" – Anton Bruckner
26. Symphony No. 4 in A major "Italian" – Felix Mendelssohn
27. Symphony No. 38 in D major "Prague" – Wolfgang Amadeus Mozart
28. Symphony No. 3 in C minor "Organ" – Camille Saint Saens
29. Symphony No. 94 in G major "Surprise" – Joseph Haydn
30. Symphony No. 101 in D major "The Clock" – Joseph Haydn
31. Symphony No. 5 in B flat major – Serge Prokofiev
32. Symphony No. 5 in E minor – Peter Ilyitch Tchaikovsky
33. Symphony No. 104 in D major "London" – Joseph Haydn
34. Symphony No. 9 in D minor – Anton Bruckner
35. Symphony No. 5 in E flat major – Jean Sibelius
36. Mathis der Maler – Paul Hindemith
37. Symphony No. 1 in D major "Classical" – Serge Prokofiev
38. Symphony No. 8 in C minor – Anton Bruckner
39. Symphony No. 8 in G major – Antonin Dvorak
40. Symphony No. 7 in D minor – Antonin Dvorak
41. Symphony No. 2 in D major – Johannes Brahms
42. Symphony No. 3 in E flat major "Rhenish" – Robert Schumann
43. Symphony No. 2 in E minor – Sergei Rachmaninoff
44. Symphony No. 4 in B flat major – Ludwig Van Beethoven
45. Symphony in D minor – Cesar Franck
46. Symphony No. 100 in G major "Military" – Joseph Haydn
47. Symphony No. 4 in D major – Gustav Mahler
48. Symphony No. 8 in E flat major "Symphony Of A Thousand" – Gustav Mahler
49. Symphony No. 2 in G major "London" – Ralph Vaughan Williams
50. Symphony No. 1 "Titan" in D major – Gustav Mahler
51. Symphony No. 103 in E flat major "Drum Roll" – Joseph Haydn
52. Symphony No. 8 in F major – Ludwig Van Beethoven
53. Symphony No. 5 – Carl Nielsen
54. Symphony No. 5 in D major – Ralph Vaughan Williams
55. Symphony No. 3 in A minor "Scottish" – Felix Mendelssohn
56. Symphony No. 1 in F minor – Dmitri Shostakovich
57. Symphony No. 7 in C major – Jean Sibelius
58. Symphony No. 4 in F minor – Ralph Vaughan Williams
59. Symphony No. 1 in B flat major "Spring" – Robert Schumann
60. Symphony No. 45 in F sharp minor "Farewell" – Joseph Haydn
61. Symphony No. 3 in D minor – Gustav Mahler
62. Symphony No. 92 in G major "Oxford" – Joseph Haydn
63. Symphony No. 3 "The Camp Meeting" – Charles Ives
64. Symphony No. 35 in D major "Haffner" – Wolfgang Amadeus Mozart
65. Symphony No. 1 in E minor – Jean Sibelius
66. Symphony No. 4 in A minor – Jean Sibelius
67. Symphony No. 88 in G major – Joseph Haydn
68. Symphony No. 1 in A flat major – Edward Elgar
69. Symphony No. 6 in A minor "Tragic" – Gustav Mahler
70. Symphony No. 7 in E minor "Song of the Night" – Gustav Mahler
71. Symphony No. 4 – Charles Ives
72. Symphony No. 4 in D minor – Robert Schumann
73. Symphony No. 3 – Aaron Copland
74. Symphony No. 29 in A major – Wolfgang Amadeus Mozart
75. Symphony No. 4 "Inextinguishable" – Carl Nielsen
76. Symphony in Three Movements – Igor Stravinsky
77. Symphony No. 5 in B flat major – Franz Schubert
78. Symphony No. 36 in C major "Linzer" – Wolfgang Amadeus Mozart
79. Symphony No. 1 in B flat minor – William Walton
80. Turangalila Symphony – Oliver Messiaen
81. Symphony No. 5 in B flat major – Anton Bruckner
82. Symphony No. 3 for soprano or tenor & orchestra "Pastoral" – Ralph Vaughan Williams
83. Symphony No. 102 in B flat major – Joseph Haydn
84. Symphony No. 3 "Symphony of Sorrowful Songs" – Henryk Gorecki
85. Harold en Italie – Hector Berlioz
86. Symphony No. 2 – Charles Ives
87. Symphony No. 2 in C major – Robert Schumann
88. Faust Symphony – Franz Liszt
89. Symphony in C major – Georges Bizet
90. Symphony No. 3"Sinfonia Espansiva" – Carl Nielsen