I'm pretty liberal, I think, and I have been very pro-charter school. I was on the board to start a charter school (two times), and have been very involved.
One of my biggest beefs with educational theory in general is the panacea approach. I see over and over again something that works well in one context and then it's leapt upon -- there! It works! Let's do it everywhere!
It's at the "let's do it everywhere" stage that it tends to fall apart.
Charter schools fall into that category too, in my experience. A lot of them are really, really good. Especially when the whole thing started. But as it has become more widespread and more panacea-ish, the quality is definitely deteriorating. Some are still very very good. Some are even worse than the public schools that they're trying to replace.
The lack of oversight is both a great way to foster innovation and a real temptation for ne'er-do-wells to grab some money.
This means that my enthusiasm for charter schools has become somewhat tempered since I was very involved (about 1996-2002).
So while I don't think there are any panaceas, I think one of the biggest single elements is elevating the pay and prestige of teachers. I think "Teach for America" is a really good program and is a step in that direction. Giving the really bright students an incentive to get in there and start teaching as a career. I was just reading about a really interesting school that was created in large part by former Teach for America people.
When all other things are equal -- curricula, buildings, resources, etc. -- it is the individual teachers who make the biggest difference. This is a long-term impression I've had that has been reinforced by more and more studies.
That's just one element of a really huge and really messy equation, though.