I am in the same boat that you are in with regards to being a reformed rocker. For what it's worth, here are the songs which I play, though, many of these songs are not hymns but are Christ-edifying and tell a short story of American History.

Who Is The Man - From the Puritans
When Jesus Wept - From the Colonials, William Billings, first American songwriter
'Twas In The Moon Of Wintertime - From French Jesuit priest missionary to the Huron Indians
How Firm A Foundation (Favorite of President's Jackson and T. Roosevelt)
*Poor Wayfaring Stranger - From the Great Awakening of the 1740s
Swing Low, Sweet Chariot - From the Plantations, before the Civil War
*Joshua Fought The Battle Of Jericho - After the Civil War
*Jacob's Ladder - Campground meeting?
*He's Got The Whole World In His Hands - recent
*Michael, Row The Boat Ashore - From the Islands off of North Carolina
*Kum-Ba-Ya
When The Saints Go Marching In
*Down By The Riverside
*Mary Don't You Weep, Don't You Mourn
*Mary Wore Three Links Of Chain (also known as "Hold On")
*Rock Island Line
*Home In That Rock
*Come And Go With Me
Ninety-And-Nine
*Old-Time Religion
*No Hiding Place
Cowboy's Dream - Actually recited by a cowboy over another's grave when there was no parson on the frontier. (For a fascinating read, check out "Bible In Pocket, Gun In Hand" by Ross Peres, 1963, regarding frontier religion.)
Ghost Riders In The Sky - "Then cowboy change your way today or with us you will ride, tryin' to catch the devil's herd, across the endless skies."
Headin' For The Last Roundup
*Old-Time Religion
*Lonesome Valley - This is actually a misnomer, it says "You've got to walk it all alone, which can never be true for a Christian)
Royal Telephone

All the selections with a * I learned from the Mel Bay Publication: "Mel Bay's Complete Folk Guitar" by Jerry Silverman. In addition, go to www.ccel.org (Chrisitan Classics Electric Library) and there is a facsimile edition of the Southern Harmony from the 1830's. A fantastic resource. In addition, Mel Bay Publishing puts out a book called "Complete Gospel Guitar" by Duck Baker. Mel Bay has quite a few other hymn collections; also, Burl Ives has two volumes of very well sung Hymns "Songs I Sang In Sunday School", etc.

In addition, I am not sure if you are familiar with a song called "House Carpenter" but, the lyrics veil a Christian warning about leaving Jesus to pursue the things of the world which drown men in perdition.