Hi,
I am familiar with the Cornell PAM Program. In fact, I was a student in it and left it before I finished the doctorate. I can provide you with more inside information about it and my opinion about it but take it with a grain of salt.
(1) The PAM program is basically at the bottom of the social science programs at Cornell. The quality of the students is the lowest (as compared to the Economics, the AEM and the Johnson School). Most of the students come from state schools, and non-top foreign or second/third tier liberal arts colleges. In the past 5-6 years, there have been quite a few students (probably anywhere between 10-15) from the Economics PhD and the AEM PhD who after they failed their generals, they were able to transfer into PAM. Somehow the DGS (the director of graduate studies) is not concerned with that this might create the impression "if you are not good enough for Economics or good enough for Applied Economics, you can always be good enough for PAM". Since many of the PAM/Economics/AEM students take courses together, this has further solidifed the opinion of Economics/AEM graduate students that the PAM Department is safe and subpar option for them in case things don't work out with their generals. You can imagine why quite a few PAM students doing economics research feel quite inferior to their Economics peers (note not all, though the majority of PAM students work in Economics)
(2) Several of the PAM professors, most prominently Don Kenkel, Liz Peters and Kosali Simon are actually more prone to the idea of working with Economics PhD students (on health or family economics research) with them than with their own PAM PhD students. This translates into likelihood of being assigned to a not-so-great TA-ship versus being able to get grant fellowships from the Human Ecology College or nice RAships. It also means that most of these faculty members will readily open up their schedules for their Economics so-called "PAM-based Economics PhD students" than their own "PAM PhD students".
(3) The quality of placements is beyond bad. Even the Cornell Economics PhD Program has been battling aweful placements in the past decade (one can see them on their site) to the point that they have been acknowledged by their DGS. At PAM, the situation is much much worse. For example, only one person who graduated from the Cornell PAM PhD in recent history was able to get an academic position and that position was with the University of Wisconsin Consumer Science Department. The rest of the PAM PhD students get some NGO or post-doc position because most are unable to get any academic offers.
(4) Finally but quite importantly the core group of people in PAM are pretty old school and not open to students doing research outside of their narrow domain of domestic welfare and health issues (despite the department suggesting a broad focus on policy research). The only way to succeed in that group as a graduate student is if you work on an issue that relates directly to their own work. This is manifested in subtle ways when you apply for different grants that are decided by them. So, if you are interested in domestic topics that relate to policy but not to obesity/cigarette smoking/disability/health insurance/or family formation, you will be pretty much out of luck.
Ithaca is a great place but I can not speak highly of the PhD Program in PAM. I'd be very worried about the time investment and the wider academic perception of my credentials once I obtain the PhD, if I were heading there. This is more or less why I decided never to finish it. I am pretty sure that one will be better off with a strong master's from a top top school than with a PhD from one of the state colleges of Cornell that is not at all highly regarded in the academic world. Unless you have family, geographic reasons or it is a really really good match with the current faculty research, I would enthusiastically discourage students to go to the PAM PhD.