look at it this way, In Mexico we have 9 political parties and to tell you the truth... it's just a big circus, and no matter who wins it's all the same because most of them spawned from the strongest political party, they make so called alliances and at the end we have 2, maybe 3 real choices at election time, the money wasted on them is incredible, one thing I think many americans have not understood yet is that no matter who wins it's still going to be the same, nothing really changes, people will complaint and the current president will always be the worst ever, so it doesn't matter who wins, I believe the progresses being made in human rights for example are just the natural progression of society and not the result of a political party winning.
you wonder about having a third party, you should keep two, as I told you before we have 9, and last time the president of my country won with only 12% of the possible votes, nonsense