Fred Armisen does Obama and he's doing the best with it that one can. Jason Sudeihes does Biden and it too is the best one can do with it. Neither offers salient personal characteristics to impersonate.

However, Palin's high pitch intonation, her dropping of "Gs" at the end of words, her "oh shucks" expressions, and her glaring lack of knowledge about the Constitution all p[rovided a rich pool of imitatable behavior and mannerisms.