My favorite live shows I've seen include (in no particular order):
Tool (awesome light show)
Shinedown (great energy)
Creed (See them every time they come around. I think it's like 4 or 5 now.)
Ra (my personal favorite "unknown" rock band. Saw them half a dozen times. They're awesome!)
Sevendust (amazing drummer. Saw them 3 times)
Pearl Jam (great, great live music. Awesome sound.)
I've also seen:
Disturbed, Nickelback, Trivium, All That Remains, Five Finger Death Punch, Shadows Fall, Drowning Pool, Staind, Seether, The Rolling Stones, Journey, Heart, Cheap Trick, Breaking Benjamin, Halestorm, Live, Cake, Trapt, AlterBridge, Papa Roach, Three Doors Down, Theory of a Deadman
And years ago, during my country days:
Randy Travis (favorite among this group), Vince Gill, Patty Lovelace, Sammy Kershaw, Brian White, David Allen Coe