The House and Senate should be dissolved. The days of having to have a very small group of people represent a larger body are over, largely because of the internet age. There is no need, any longer, to have these folks pretending to vote for those they pretend to represent. It's also high time that the populace is actually forced to take a larger role in this country. 1 Person, 1 Vote. The President and Cabinet would propose legislation, maybe have a think tank on hand to help write up legislation/amendments etc... then the President pitches it to the people, and the people vote on a bi-monthly basis (for all proposed legislation/amendments). Tie the vote to SSN# to avoid fraud.
In this sense, we crush special interests, we crush lobbyists, and Citizen's United becomes irrelevant, because they'd no longer be able to really influence anyone other than the President, and the President can't enact legislation w/o the populaces backing. You'd still retain the structure of Democracy, and you'd still (obviously) retain the Office of the Presidency and their cabinet (would be needed for foreign affairs, etc...), but the actual voting would be the responsibility o f the populace, and not up to less than 600 people to decide for a country of 310+ million.
I'm sure there are issues with this idea, but I think the bottom line is that the House and Senate are simply no longer necessary in a time where you can inform the populace about virtually anything, and it doesn't take days/weeks for news to travel from one side of the country to the other. This would also have the added bonus of getting more people directly involved in the political process and hopefully encourage people to learn more about the things they vote on.
Democracy, so good people should be forced to partake in it. Yikes!
The whole point of the U.S system, which is a good point, is that there are some things the majority shouldn't be able to vote on. The minority's rights must be protected against mob rule. A pure democracy is dangerous for this reason. That is the why a representative legislature is necessary. They consider both the majority opinion and the protected minority rights when making laws. It is also why even on the local government level, when there were only a few hundred people, votes weren't tallied directly but rather through trusted representatives.