I don't know how much of a showdown it is going to be....
Anyway, all the suggestions are great. I suggest searching the forum for "Foil Hat Rub". It is fantastic.
Now, with that said, I usually don't use too fancy of a rub on pork butt because it always seems to get lost in the porky deliciousness. It just seems like kind of a waste. However, on anything else, go for it.