Read Matt Yglesias's case for parliamentarianism. If you want my opinion, a British style system, minus a House of Lords, seems damn near ideal.
The one thing that nobody seems to want to mention with respect to the Constitution is that it has some pretty obvious flaws for the age we live in. This is not to diminish from the Framers, but they were writing a document based on 18th century realities. It is intentionally very difficult to pursue fundamental change under the Constitution because the Framers didn't want that. There was no need to change things too quickly back then, especially with their conception of the federal government.
Nowadays, having a fast-acting government seems like a necessity. And we simply don't have one. The government is set up to allow small groups of people--such as small state senators--to stop majoritarian measures pretty easily. That was the Framers' fault, though a necessary one if one wanted to retain the whole quasi-sovereign states concept (which seems silly now). But I highly doubt the Framers thought their system would still be in service, unmodified, two centuries later. Parliamentary governments are much more dynamic and must necessarily be more centrist and responsive to public opinion--they can do whatever they want, but so can the other side if they win. Britain, for example, has historically had a far more moderate political culture than America (Thatcher notwithstanding) because of these realities. I suppose my major gripe with our political system is that there are too many checks and balances. The Framers were a excessively concerned about concentrated power and overcompensated to avoid a system that created an all-powerful king. As we've seen during the Bush years, you can build in all the checks and balances you want, and it's not going to matter if nobody else wants to take responsibility aside from an elected king. What is needed are better public servants.
I wonder about the extent to which right-wing conservatism has prospered in America simply because the political system is set up to keep major change from occurring, thus facilitating a message of "government doesn't work." Obviously, it's silly to say that the Constitution is the only reason why someone like Reagan came to power. But I don't think the inertial effect of the system is negligible in the rise of the Right.
