Washington wins at home. Seattle was undefeated at home this year but only won 1 game on the road. The road/home splits are ridiculous for this team. FedEx Field, like others have said, will be insane. Shannahan has the advantage in coaching experience in big games over Pete. I think Shannahan will be able to come up with a good enough game plan to shut down Russel Wilson.
Seattle has a better chance to go all the way if they win than Washington IMO.
Also, I definitely give Shannahan the edge in coaching, but Carroll is no slouch. He's always had his teams loose and playing extremely well in big games. I don't expect this to be any different.
I think this will be the best game of the weekend without a doubt.