As to the parents, definitely.

Can’t hurt for the kid to write some. Obviously the level of the discourse in the kid's note will be different from what our rising ninth grader did. We started our girls at their primary school in the infant/toddler division. Definitely no thank yous there but I think it would be charming and notable from a fourth grader.

Hope you find the right school for yours. Don’t let this place discourage you or steer you towards prestige over fit.

PP...does your suggestion also apply to those parents and children in lower school? We have a 4th grader applying this year and was wondering if we should follow your advice on the thank you notes...

As to parent interviews, our experience varied depending on the school. The catholic schools did not do one. The independent schools did. One asked fairly detailed questions about our expectations for our child, how we viewed her strengths and weaknesses, etc. It was conducted by the same interviewer who interviewed our child and he noted that part of what they wanted to see was parent expectations and desires (and realistic assessment of the child) that lined up with the child's. I understand that others had even more pointed questions at that school but we may have escaped those because it was my alma mater. At another, there were similar questions plus questions about our family dynamics and educational background, why we were interested in the particular school, etc. But fairly high level and, again, not very pointed. We were pretty active throughout the search process and that may have made the interviews go a bit easier as the admissions folks at each knew us fairly well. We are aware that other parents had differing experiences.

In both cases, we asked more questions of the interviewer than the interviewer asked of us. I believe that asking knowledgeable and relevant questions about the school is the number one thing a family can do to make for a good parent interview. Do your research and come prepared with questions. You are far better off preparing to ask questions than to answer them.

As for thank you notes, we wrote paper notes to each of the ADs and to the interviewer (if different). Our child also wrote to them and also to their shadow host (although the shadow host by email rather than paper). Once our child had narrowed down to a top choice, we followed up with a letter to the AD at that school indicating that it was our top choice and our child did the same. I also emailed thanks to a couple of the admins who went above the call in helping to schedule and (in one case where there were weather issues with the original visit) reschedule or in answering questions about the application.

Good luck to you!