The Newsweek polls are fairly awful. Gallup's are really bad right now because of how heavily they are weighting democrats in their surveys. I think PPP and Rasmussen Reports are pretty good.
I have completed a detailed analysis of the internals of two dozen major national pollsters, and have found the following:
Excellent
1.PPP
2.NPR
3.Rasmussen
Terrible
1.CBS
2.Politico
3.Ispos
BTW, you are correct that the Newsweek polls (Princeton Associates) are extremely biased.
What is interesting is that PPP and NPR polls are run by Democrat pollsters (NPR by Clinton's pollster)