Speaking of the Senate, just looking at the vulnerable seats in 2016 makes me kind of want a Hillary candidacy because it would assure a Dem landslide in congressional races as well.
http://en.wikipedia.org/wiki/United_States_Senate_elections,_2016
Florida, Ohio, New Hampshire, Illinois, Pennsylvania and Wisconsin will be easy Dem pickups.
The Dems also have a good shot in Arizona (if McCain retires), Alaska (if Murkowski gets primaried out), Georgia, Indiana, Iowa (seeing Grassley lose would be awesome), Kentucky, Missouri, and
North Carolina.
So best case scenario is 12-14 seats, if the Dems hold onto the Senate this year they can get well above the filibuster proof majority in 2016.