I'll give credit to my (obscure) D congressman, Bill Owens, for doing some leadership in removing the odious clause in Obamacare about the 1099 for all.
I'll give credit to Andrew Cuomo, my D governor, for not being a complete moonbat, and recognizing that being the tax capital of the country is a losing proposition for the state's future, and people are running for the hills (in other words, Florida. I'm making plans myself).
That's two examples, but what you're probably looking for are instances of D's acting like D's, not R's, correct?
I'm drawing a blank. All the D's ideas and plans come with unintended consequences which they never think through. They never account for the fact that you tax behavior you want to discourage, and not tax behavior you want to encourage, like economic prosperity.