Congratulations on your upcoming wedding!
Depending on your venue, and level of formality, there are a lot of beautiful choices for you to consider. Listen to Aaron Copeland's opening "fanfare for the common man", any of the four seasons concertos by Vivaldi, or a selection by Pachelbel, (light classical) and Beethoven's Ode to Joy, also known as Jesu, God of man's desire.
Outside of the box suggestions? A handbell choir can ring you out, (many schools or churches have bell choirs that welcome an opportunity to perform for a nominal fee). A Gospel choir can begin with a version of "Oh Happy Day" as you travel down the aisle.
Whatever you choose, make sure YOU love it. It could be one of the most magical moments in your lives, and the music you walk to will always help you relive the feeling.