Yeah, it's probably time. Unfortunately.
What we did in the past was much more complex. As Ben points out, the two parties tended to be driven toward the center -- that is, the system itself tended to move toward consensus. The system used in other countries, with multiple political parties and coalition politics, still existed here, but within the two mainstream parties rather than at the top level. There are still remnants of that, mainly visible among the Republicans because their extreme wing (the Religious Right) is much more visible for several reasons than the extreme wings of the Democrats.
I say "unfortunately" because unlike parliamentary democracies we have a very strong chief executive. Our President is essentially a King with term limits; the only real check on Presidential power is the fact that he has to leave after eight years. Having the President as the visible chief of some whacko coalition is going to be very dangerous, folks.
The ultimate result is gonna be Italy -- more or less total inability to elect a Government. If you want to put this system into place, please start thinking about what happens when we can't put a coalition together to select a President, and the whole system is run by unelected bureaucrats for extended periods of time.
As for the mechanics and getting people to understand it, might it not be easier to assign points? Instead of making people make two different choices (first and second), tell them to assign +1 to the ones they really like, zero to the ones they can stand but don't really care for, and -1 to the ones they hate. The labels might be "Like", "Don't Care", "Hate", but the counting system would function on the numbers. Highest score wins.