Forget 2016...

[EmersonAdams]

I'm looking more towards the next generation of politicians, so most of my suggestions are a little out in left field. I'm trying to leave out people being considered for the presidency in 2016, so I'm not rehashing the same talking points.

San Antonio Mayor Julian Castro- He's young, latino, charismatic, and a raising star in a state that's looking to trend more and more democratic in coming election years because of demographic shifts. Castro would be an interesting choice to headline a gubernatorial ticket against Perry (should he seek a third term and win the Republican nomination) or another statewide office in the coming years.

Newark Mayor Cory Booker- This man is superman. He shovels snow from old ladies driveways and saves women from burning buildings. He's got a dramatic flair and a solid record behind him, and he looks like a top prospect to run against Republican darling Chris Christie in 2013. If he can take and hold the governorship for a couple terms, he could be a major player in 2020.

California Lt. Governor Gavin Newsom- As Mayor of San Francisco, Newsom earned a national following for his dramatic support for gay marriage. He's very charismatic, and is next in line to be governor of the state after Jerry Brown (especially if he declines to run for a second term, given that he would be close to 80 by 2014).

California Attorney General Kamala Harris- She aggressively perused a harsher settlement against the banks during the state-lead foreclosure malpractice lawsuit. Her work will benefit millions, and she could be a successor to Feinstein or Boxer should they retire at the end of their next senate terms. She is a women and a minority (part african-american and part indian/tamil american), which would play well to the base.
 
New York Attorney General Eric Schneiderman - Both of the last two elected democratic governors of New York were previously the state's attorney generals. He lead the push with Kamala Harris to get a larger settlement against the banks.

Fmr. Ohio Attorney General Richard Cordray - He is currently leading the CFPB, and he has a strong record of consumer protection though his tenure as Attorney General. He has held many state wide offices (including solicitor general and state treasurer), and he could be a serious challenger against Kasich for Ohio governor in 2014. If he won, he would have time to build up a national profile and he would be a logical choice from an important swing state in 2020.

Representative Tammy Baldwin - If she wins the senate race in Wisconsin this year, Baldwin will be the first openly gay senator in American history. She is fiery and passionate, and her strong stances on women's and LGBT rights would play well with the base. She has a long progressive record behind her in the house, and she will have time to build up a national reputation and influence in the senate if she is elected this year.

[EmersonAdams]

^^
Those are mostly 2024 candidates.  Maybe Booker in 2020 if he's elected governor next year, but otherwise those guys would probably wait until 2024.  (I know I listed Newsom and Harris as possible 2020ers, but as Joementum pointed out, 2024 is more likely.)

I think you're pretty much right. Like I said, I was trying to avoid candidates who are already being speculated to run in 2016. I will say, though, that Booker and Cordray have a significant chance at unseating the republican governors in their respective states (Christie in NJ or Kaisch in OH) by 2014, which would give them time to build credible national profiles. By the time the 2020 campaign season starts up, both could already be re-elected and serving second terms, and will have real records to run on. Baldwin is a bit of a long shot because of her sexual orientation and outspoken liberalism, but if a republican wins 2016 and support for gay marriage continues to climb, she has a shot by 2020. I do agree it could be quite some time before the rising stars in NY and Cali make it to the national stage, if only because each state is dominated by democratic incumbents. Castro has to wait it out until Texas starts becoming more of a purple state (either 2016 or later) before he'll be a serious contender for statewide office.