I think that there should be an effort to reform the UN. Currently, the UN is an association of Executive Branches. It should be modified to add a legislative branch, with the representatives being selected by vote, There should be some statement of limited powers, and a statement of passive rights (you have the right to free speech, but not to own a radio station....)
If that was done, and done well, there would be some improvement. If not done, then The US should develop a competitor, with members limited to states with limited powers and individual rights. Members states could have their territorial integrity guaranteed by the members, in return for their contribution.
Then the UN could wither away or reform. Their choice.
And why shouldn't people have the right to own a radio station?
The UN should be primarily a body of diplomats and international debate with a prime focus on preventing and stopping wars. It should also pursue humanitarian works like distrubuting medicine and food to the poor. That's about it. Political centralization is a bad idea. The recent votes in France and Holland show what happens when political elites move too far ahead of the people.
Regarding your point about a competitor international body, there is no need. The UN was not designed to be a club of democracies. It was meant to function as a means to avoid war. Therefore, some unsavory governments are necessarily going to be represented.
As for your point about the territorial integrity of members, this is already guaranteed. But it is often ignored.
I think yours is one of the most rational and plausible and best ideas yet.