For the ceremony Josh can perform traditional classical and wedding music on the piano (or organ) AND sing romantic songs (good for unity candle lightings and such) accompanying himself on piano or guitar. Then he can use all his talents to entertain at the reception with a mix of pop/rock from the last six decades of music.

Examples:

CLASSICAL/WEDDING:
Jesu Joy of Man's Desiring
Pachelbel Canon
Ave Maria
Wachet Auf
Bridal Chorus
Wedding March

CEREMONY VOCAL:
The Wedding Song
In My Life
Broken Road
True Companion
You Can Close Your Eyes
Marry Me

RECEPTION MUSIC:
Margaritaville
Brown Eyed Girl
Piano Man
Crocodile Rock
American Girl
Lady Madonna

...Dozens more!