The biggest problem with the United States, I think, is politics, and by that I mean politics for the sake of politics. It seems politicians are more interested in making themselves look good and other politicians look bad than actually running the country.
I don't know how to fix that problem, but I know what I would change. If I could snap my fingers and change the rules, I'd change two things:
First - If you currently hold a public office and are running for different public office, you must immediately resign from your old office. This really only applies to Congressmen and Senators running for President, but it really bothers me when any politician is putting all their heart and soul into campaigning and totally ignoring the office to which they were elected. Call it a pet peeve.
Second - In order to hold the highest office in one of the branches of government (Judicial - Supreme Court Justice, Legislative - Congress or Senate, Executive - President), you must have at experience as a public servant in that branch at the local, state, or federal level more or equal to twice as long as the term of the office for which you are running or 16 years, whichever is shorter.
So you would need to have 4 or 12 years experience to become a U.S. Congressmen or Senator, respectively, as a public servant at the local, state or federal level in the legislative branch. By this I mean you'd have to have been in some sort of committee style body, like a State Congress, Town Council, or even a PTA Board. Any job where you were part of a larger body that worked for or on behalf of the people.
To be President, you would have to have been a public servant serving in an executive capacity for at least 8 years. Such jobs would include Governor, Mayor, Sherriff, or a member of the Armed Forces, Peace Officer, or other Emergancy Personelle where you were in the position to lead; where executive decisions had to be made that affected people's lives.
And of course to be a Supreme Court Justice, while not elected, you would have had to have worked in the Judicial branch as a public servant, meaning either as an District Attorney, ADA, or Judge. Since a Supreme Court Justice is appointed for life, you would need 16 years of experience (2 x 8 years, the next logical progression in doubling terms in office at the Federal level - 2 years Congressmen, 4 years President, 6 years Senator).
How would this change things? The way I see it, at least politicians could start debating the issues more, and talk about experience less. They could still play the game of 'my experience is better than yours', but at least they couldn't play the 'you have no experience game'.
Plus, who knows, we may actually get qualified people in those positions.