In Rubio's case it would likely be someone of an elder statesman quality to balance out the lack of experience perception.
For Hillary, Yes it may be too soon for Castro but then again look at Obama's rise to fame. The Clinton's tend to keep a "list" of people who have wronged or pissed them off in the past. I doubt she would select someone who chose to endorse Obama over her early on in the 08 primaries. Unless she really truly thought she needed them to win. With that said I think she goes with someone quite a bit younger and energetic without overlooking the too wet behind the ears qualities.
This.
The Clintons are loyalists, and she would more than likely select someone who endorsed her over Obama in 2008. I don't think she would go with a Latino, seeing as how she was (and is) extremely popular with them in 2008 (I think she won them by a 2-to-1 margin over Obama). I say she would probably have to choose an African American because I'm sure several in the African American community will remember her as the one who dared to challenge the first African American candidate (how dare she do something like that!). Having said that, there weren't many prominent elected African Americans who supported her in 2008; the only ones I can think of (who still hold offices) are Maxine Waters, Emanuel Cleaver, Ron Dellums (Mayor of Oakland), Michael Nutter (Mayor of Philadelphia), Charlie Rangel (and I believe all of New York's black delegation - Gregory Meeks, Yvette Clarke and Edolphus Towns were for her as well), and Sheila Jackson Lee. I don't see any of these as VP material, though I do agree that she would more than likely choose one of her first candidacy's endorsers.
According to the latest polls, black voters hold no animosity towards the Clintons. So there is no reason for her to pick an African-American running mate.
