A few early thoughts on the Clinton-Kaine ticket:
It’s about as conventional a ticket as one could find. Kaine does offer some interesting backgrounds in his biography (e.g. his religiosity, bilingual skills, and family background) that will further shore up the parts of the Democratic electorate where the risk of turnout slippage is considerable (e.g. ethnic minorities), but it is not especially extraordinary. It will further weaken Trump’s chances, though, by reducing the Democrats’ inevitable bleeding (of the ethnic voters) compared to Obama’s performance in 2012.
On the socio-economic front, there is zero concession to the Sanders wing, although probably not a cold snub (not that it would have been wise for the Democrats to have pulled something like that off anyways). Kaine is a standard middle of the road Democrat, who apparently subscribes to the usual DLC fare (possibly even somewhat more pro-business/pro-free-market than the average–he was a Southern governor, after all.). He will not excite the “missing white voters,” even those who went Sanders rather than Trump.
So the pick of Kaine shores up the existing Democratic base rather than change the game. This is perfectly reasonable strategy: Republicans are those who are behind, and they are the ones who have to gamble by changing the game and take on new risks, not the Democrats. At minimum, Kaine reduces the chance that the Democrats will draw the short stick between now and November–a very real possibility with someone as controversial as the Clintons on top of their ticket. If Trump is to win in November, he has to count more on his own lucky star, rather than the Democrats’ unlucky one.