The Heritage Foundation has proposed a "Marshall Plan for Marriage." The first item is to end the marriage penalty in several tax or benefit programs of the federal government. The marriage penalty occurs when married couples pay more than the same couple would if cohabited without marriage because their combined incomes push them into a higher bracket than each of their incomes would be if taken separately.
For two of their three proposed improvements there is already bipartisan support. The marriage penalty was largely eliminated in the federal income tax and the Earned Income Tax Credit in the last decade. The budget compromise reached last fall extended those fixes until 2012. Heritage proposes making those fixes permanent. This seems to me a sensible move that majorities in both parties can support.
The third proposal is to eliminate a marriage penalty in the health reform act. There has not already been a bipartisan move to fix this problem. However, since this marriage penalty is like that in the income tax and the EITC, I think both sides could agree to work together to fix this problem, too.
Legislation that brings the parties together and supports marriage seems like a win-win.