On "Don't Vote for Bernie" Logic
I don't have a horse in this race, but I read lots of people on the web (e.g. Dave Winer) saying don't vote for Bernie, because (if he wins the Democratic nomination) then the Republicans will win in November. This makes little sense.
If Hillary Clinton can't beat Bernie Sanders, (and she couldn't beat Barack Obama, so this is a distinct possibility) why does anyone think she would nevertheless be able beat a magician like Donald Trump (or whomever, should Donald implode along the way) while Bernie would not be able to?
Let's think this through:
Democrats H v. B
Republicans D v. N
(H=Hillary, B=Bernie, D=Donald, N=Not Donald)
Let's further assume that the winner in each race has majority support in their party, with at least enthusiasm from their supporters, which has been the case in most primary elections by the end.
So at this point there are 4 possible general election contests (sorry Martin),
H v. D, H v. N, B v. D, B v N
The probability of Hillary having been able to defeat D (or N) when she received less than half the support in the Democratic primary (and loosely say less than 25% strong support nationally, since Independents and Republicans don't like her) two campaigns in a row (2008, 2016) seems weak.
For this to be true, one has to assume there are more Independents who would swing to Hillary but away from Bernie than the converse. This may hold if Hillary is perceived as more moderate and Independents were moderates, but that is not really the case.
One also has to assume that Bernie voters are more likely to turn out for Hillary than Hillary voters would be to turn out for Bernie. There is no evidence for this assumption, and the converse is more likely to be true, since Bernie is the insurgent. (Similarly, I think it is plausible that non-Trump republican voters are more likely to turn out for Trump than Trump primary voters are to turn out for non-Trump, since Trump is attracting less mainstream voters, while party members want to win).
Sure the Democrats (or Republicans) will rally round the nominee, but as someone who was not preferred by the party she is purported to lead to victory in the General Election, she will not generate much widespread enthusiasm. The slogan "Resigned to Hillary" says it all.
Given the General Election contests are often tight, not having support of your own party is a problem (Bush '92, Carter '80). Given the possibility of a third party centrist candidate, this is even more tenuous, since the centrist will pull more from Hillary than from Bernie.
Being the first woman President will be attractive to some (and repulsive to others), perhaps, but so will the first Jewish President, or the first Canadian President, or the first Billionaire President, or whatever other socio-ethnic group is chosen.
In the event that Bernie won the nomination, it is evidence (in a Bayesian sense) that this "history" was not even important enough to her own party to nominate her.
So vote for who you want to be President, it's like buying a lottery ticket but free. Not voting for someone because of how someone else might vote in the next election (when the probability of your vote being decisive is pretty close to zero) is silly, the kind of FUD the Clintons are known for.