The Interlude is defined as that point after your ceremony starts where there is a period of quiet reflection. This might include the lighting of the unity candle, the symbolic mixing of different colored sands, or other special observance.
There are a lot of choices for music during this period. Many couples use this time to feature a talented family friend or relative in singing or playing an instrument. If the budget permits, a professional wedding singer might perform here. Be sure to check with the band you've hired to see if one of the band members can perform this function. This will save you from the expense of a separate hire.
The music shouldn't be too loud, as the point of the interlude is to have reflection on the symbolism of the event. An "interlude" really is a period between two points. You can view it as a period between the begining and ending of your cermony.
Here are some top interlude songs:
A Moment Like This. Kelly Clarkson
When You Say Nothing At All. Ronan Keating or Alison Krauss
It's Your Love. Tim McGraw/Faith Hill
Love of My Life. Jim Brickman w/ Michael W. Smith
Forever and For Always. Shania Twain
I Can Only Imagine. Mercy Me
Here and Now. Luther Vandross
I Cross My Heart. George Strait
My Best Friend. Tim McGraw
Ribbon In The Sky. Stevie Wonder
Only Time. Enya
Grow Old Along With Me. Mary Chapin Carpenter
Truly, Madly, Deeply. Savage Garden
First Time Ever I Saw Your Face. Roberta Flack
In My Life. The Beatles
With modern technology these songs can be altered to remove the vocals, if you like, or presented in the original form. Sometimes the instrumental version of the original recording is tremendously effective, as the audience is "singing" the words mentally. It adds to the quiet reflection and beauty of the event, as all consider the meaning of the lyrics, and how they relate to your special day.