The music during your wedding can be very important, especially if there are a lot of people. It cues participants. It let's everybody know what's happening and when there is a transition. It's in the background and pleasant and subconscious - not a blaring announcement. The more recognizable and traditional the music, the easier it will be for many, especially the older, people to follow along. That said, your wedding should be uniquely yours. That means chose music that you like, that is important or special to you and your wedding party. Your music can be recorded or live, played by a musician or group or sung a capella. Or choose no music. If your wedding ceremony takes place in a natural setting, you might really like having the music of the wild birds, or wind through the trees, or water flowing. The choice is yours.
Here's a great site with a lot of wedding song suggestions:
http://www.weddingwire.com/wedding-songs