Cooper AT3 XLT, Firestone TransForce AT2, Michelin Defender LTX M/S2 have all done very well for highway usage at our shop with our roads/climates. Your climate and road makeup (cold paved VS hot paved VS concrete etc) will definitely change tire life compared to others.
Most of the roads here are cold paved and our summer average highs are in the low to mid 80s with a 55mph speed limit.