Be sure to check the choirs schedule. Went to SLC thinking we could see a mass, no such luck as they weren't singing at anytime I was there.
And regards to driving. I've driven across country a few times. Enjoy the ride, and don't put yourself on strict schedule. Stop and smell the roses. Unless you were like me once where I made it to No. CA in 72 hours to deliver a part to the electric company so they could get Sacramento back online.
Safe travels.