I'm a huge classical music nerd and it was a big influence on our selections.
Prelude Music: String Quartet No. 3 by Philip Glass Processional: The Great Gate of Kiev (arranged for strings) by Modest Mussorgsky Recessional: Final Hymn from the Firebird Suite by Igor Stravinsky
We're having a Catholic wedding, so all of the music is required to be either religious or classical. I am a big classical music nerd thanks to piano lessons and 9 years of being an orchestra kid, so that restriction is just an excuse for me to pick all of my favorite composers.
Processional (families + wedding party): Bist du bei mir (Bach)
Bridal entrance: Sheep May Safely Graze (JS Bach)
Recessional: Arrival of the Queen of Sheba (Handel, from Xerxes)
I'm also incorporating a lot of my favorite hymns throughout the mass, including Be Thou My Vision, Simple Gifts, and O God Beyond All Praising (same tune as the Jupiter theme from The Planets).