Normally the Vice Presidential pick for a presidential election doesn't mean much. The last VP to "balance a ticket" was Lyndon Johnson (who did bring Texas into the fold for JFK), but in the past few cycles just who was selected to be the second banana hasn't been important Of course, you could argue that Cheney as an important pick since Bush let him run a large part of the government, but generally the job consists of going to State Funerals and that's about it.
Of course, in this particular election season you could also say that, like everything else about modern politics this time, things have changed. In particular, who Donald Trump picks to be Vice President is particularly important.
If Trump wins, I think that there's at least a 50/50 chance that he will be impeached - not only because he's probably going to do some crazy stuff if he is elected, but this will be a neat way for the Empire, er, the Republican establishment to strike back and re-establish control while keeping their hands clean. And then there's the stuff that Donald has managed to duck for the past 30 years as a business man that he won't be able to stiff arm if he's president. Yes, Donald, there are different standards for politicians and there are large bureaucracies (some of which you won't control) that uphold them.
So that makes his selection of a Vice Presidential nominee particularly important, because that person may be running the country at some point.
Just when you thought that a Trump presidency could just about be the scariest thing that you could imagine ...