I am a PA resident so the hidden gems that I know are local to here.
-Cook Honors College at Indiana University of Pennsylvania (IUP)
-Juniata College
-Susquehanna University (*mentioned here on CC by a few regular users but basically unknown)
-Lycoming College
-Franklin and Marshall (used to get a lot of love but have not seen anyone mention anything in a few years of lurking)
-West Chester University