We definitely need to get some new ideas and new blood in there somehow. There are so few debates that each moment is potentially "take or break", though, and if we had a bunch of third party candidates in there, we'd see some real wackos get significant percentages of the vote.
I'd like to see some more diverse types of debates and more of them with various rules and participants - make it fresh and interesting. Also lacking in the US two-party domination is any sort of proportional representation, which is another way to get new ideas into the legislative process.