I see what you guys are saying, but I don't necessarily know how much impact they really have on the entire process. The press make a big deal out of the Iowa Caucus and the New Hampshire primary, because there is a feeling that the results may be very 'typical' of the nationwide results since the voting populous of those two states may, in some eyes, be seen as a typical cross section of America. (Iowa may be more the Republicans cross sections and Hew Hampshire the Dems.
The results in Iowa haven't even been all that accurate as an indicator.
For the Dems:
In 1972 and 1976 "Uncommitted" carried the vote (the eventual nominees received less then 30% of the vote.
In 1988 Dick Gephardt blew Michael Dukakis out of the water.
In 1992 Iowa Native Tom Harkin thumped everyone (Bill Clinton got 3%)
For the GOP:
1980: G.H. W. Bush edges out Ronald Reagan
1988 Bob Dole and Pat Robertson beat G.H.W. Bush
Now for when these are held, the states set up the dates, and has a good deal to do with economics. Would Iowa make any money if their caucus was held on the same day as anywhere else on earth? No way. As it is, the state stands to bring in a ton of revenue, so there would be no motivation for them to move the date. Plus candidates don't have to try to spread their campaigns too thin.
It does get very overwhelming though, living in those states. Over the last three election cycles I lived in Iowa, and the senses get overloaded. The phone calls were the worst. The answering machine would be filled with prerecorded celebrities asking for a certain candidates vote.
Good luck to all in the upcoming election season.