Lee Drutman has an excellent idea for an additional (or substitutive) practice for evaluating presidential candidates:

How about, just for once, instead of a short-answer debate, we let our candidates take a long-essay test where we get to see the quality of their actual decision-making? The format could work like this: The candidates show up, and they each get an office with a computer, hooked up to the Internet, and a phone. They also get a full scenario. For example, What would they do if radical Islamists staged a coup in Pakistan and began initiating military action in Kashmir? How would they respond if China’s economy went into a tailspin and Asia began following? How would they respond if a particularly virulent flu started showing up in the United States? What would they do if a group claiming to be affiliated with al-Qaida blew up a bus in Chicago?
Then they get an hour to craft a response. They can call whomever they like, do what research they like, and talk to the scenario experts as much as they like. But every move is recorded on video, so we can see how they approach a problem. At the end, they each get 10 minutes in their office to explain how and why they would respond (this way they do not get to hear what other candidates have said).
This would be different. But it would be serious. It would give onlookers a chance to see how the candidates think through a situation, what questions they ask, and how they present a solution, given time to think about it. After all, we want a creative problem-solver in the Oval Office, not a mere regurgitator of rehearsed pabulum.

His second idea — an anonymous survey of government types — is less attractive, telling the public more who’s side has better stacked the careerists than which candidate would be effective within their world. On the other hand, it might be nice to be able to vote against their preferences.