That's a big question. I don't know if I am able to tackle it in a BB post.
I look at it this way: If I wish to live in a socially, economically, and politically stable society, then we need to have minimal wealth disparities. I don't want to live in Zimbabwe, Congo, Russia, etc. because those places are real plutocracies. People get killed there, for no more reason than they annoyed a rich person who could afford to have them killed. I don't want to live in a feudal society, and I don't want to live in 1840s southern US--again, because those societies were dangerous, and people got killed. Getting killed, as Coca-Cola, Shell Oil and other companies that operate in socioeconomically unstable parts of the world will tell you, is bad for business.
Public companies do not operate long term. Note: here I am distinguishing between privately owned companies, which can do what they please, and stockholder-owned companies. They're quite different. It is their executives' duty to create as much short-term profit as possible. If they have a choice between doing something long-term that costs short-term money, which may or may not pay off depending on how their competitors/gov't react, and doing something which may be bad for their operations long term but gets them $$$ short term, then they MUST choose the short term thing. So there has to be some regulatory balance to keep them focused on the long term. Companies, especially public companies, are a fictional construct which we agree exists for the benefit of society. When they stop benefiting society, we the public have no reason to continue to agree to that fiction.
I can see problems with the current economic models that have apparently failed Wall Street, starting with, "if you can't do math, you need to find a job that doesn't involve numbers." Personally I would like to see much of the economic modeling ripped apart and re-built using Bayesian stats and HMMs or neural nets to account for the "stuff we don't know" and iteratively self-correcting based on real-time data. And then see where that leads the theory. As it stands, most of economics looks like a pile of horse puckey to me.
One thing we desperately need to focus on is innovation, and innovation comes from education. Our education system in this country is terrible. No, not everyone can have a PhD in theoretical physics, but it's the innovators that create jobs and create products and move society forward--as in, out of the polluted, oil-dependent, ailing mess we're in. So I would pour a lot of money into education and SBIR-type grants. And I'd probably seize it from the assets of the robber barons, because if your company tanks so badly that the taxpayers have to bail your behind out, then you should be in jail breaking rocks for the sin of defrauding your investors, not on a spa vacation. The more educated people are, the healthier they are, too.
It's hard to break the cycle of poverty, but education really helps.
I am not a big fan of re-inventing the wheel. I guess I would survey countries that do seem to be getting along well, and analyze what they are doing that works. Iceland, Norway and Denmark seem to do OK. Low unemployment, good quality of life.