I'm annoyed by the speculation and, in my view, faulty analysis regarding how the president and congress will interact after the elections, especially if at least the House has a Republican majority. Nobody seems to recognize that the White House will go it alone, regardless. In the runup to reelection, first term presidents use congress as a punching bag if necessary and a co-conspirator only if it's in their personal/political interest. The insularity of Obama's White House staff only reenforces this tendency. They will focus entirely on what helps the president, not what might help Democrats in congress.
Meanwhile, congress will be more closely divided even if Democrats retain majorities. That leads to gridlock except on the only must-pass bills, chiefly appropriations to run the government. That's where the drama will be, and not on much other legislation. Both sides will bluff and threaten, and only one side can win. Calls for congress to be more progressive or more conservative or more centrist won't matter. Each side will plot how to escape the OK Corral shootout with the fewest injuries.