LOVE potomac but my one criticism is that they did a pretty terrible (well, maybe non existent) job of welcoming our child and family. Joined in a non-entry year a few years ago in the lower school and we had nothing other than come in the day before classes started to meet the teacher, but there were several other returning families there as well who took up most of the time. Mentor family did nothing (unless you consider making one phone call something, but i didn't).
Other than that, it is a lovely, warm, kind place.