I voted Haymitch for Ravenclaw, because throughout the whole series, despite Haymitch being a drunk he was always shown as being very smart. Even in his Hunger Games, it's how he won his games, by outsmarting everyone. He thinks things through and is very meticulous when giving out sponsor gifts to Katniss when she was in both arenas. I think his intelligence is clearly his biggest personality factor,and would deem him a Ravenclaw.
I am curious though to hear what other people think. I think he could be argued for other houses.