Sounds like Tire Barn might have faulty equipment or poorly trained employees. They already hosed up the first balance and the second did not seem to improve things. There is a chance you got a defective tire but 4 new tires of any brand (with a non-hardcore offroad tread pattern) should be fairly smooth at highway speeds.

I went from Dunlop street treads to the Revos about 6k ago. The Revos are WAY smoother but comparing old tires to new is a bit unfair. My 99k miles 4Runner rides smooth with no vibration or shakes up to 95 mph. The Revos are actually pretty quiet for an A/T tire too. My $0.02.