If you were designing a system to pick a Democratic presidential nominee, it probably wouldn't look much like the current primary system. The Iowa / New Hampshire sequence helps candidates who've done favors for local politicians and who are willing to perform obscene acts of submission to Big Corn. No offense meant to Jeanne Shaheen or the corn lobby (actually, on second thought, let's offend the corn lobby), but these aren’t especially desirable features in a Presidential candidate.
New Hampshire boosters say that putting their small state up front allows for more face-to-face "retail politics." But presidential elections aren't decided on the basis of retail politics, and we want the primary process to turn out the Democrat whose skills are optimized for winning the general election.
Getting more people involved has all the usual advantages of democracy, and it allows for more generally positive media attention towards our candidates. In a crowded primary field, candidates are mostly going to be putting up positive ads about themselves rather than dirtying themselves by attacking each other. This allows them to define themselves before Karl Rove can come on the scene and define them. It also allows for plenty of nice GOP-bashing that Republicans won't be given a good opportunity to respond to. Given the success that Dean got from his hammering of Bush, beating up on Republicans looks like it'll be a much better path to success than beating up on Democrats. Can we have this in more states, please?
Of all the solutions offered here, I’d say that the Rotating Primary Plan, which has four regions of the country each going at separate times, is probably my favorite. The authors of the plan have, in a bizarre concession to the bizarreness of the status quo, allowed Iowa and New Hampshire to stay out front of the whole process. Needless to say, I support a version of the plan from which that bug has been removed.