@PtonAlumnus - thank you! You are right that P is super generous with need-based aid. However, my husband works (not faculty so no reciprocity) at MIT which makes it very discounted (not free) to attend MIT. 
The difference between P and M is something that we told DS we can manage, so we’re trying not to let that be a huge factor (though it is a distraction, yes!).
I know about the wonderful Hillel, but thank you for more info on all the background and Jewish life! I notice that P also seems to be really committed to supporting diversity including religious diversity, in an open and helpful way.
Do you happen to know what the population is at a typical Friday night (sabbath) dinner at the CJL?