We connected via messaging. 
Our situations sound fairly similar (as what our kids are/were looking for). Our daughter researched a bunch and the mixed gender schools she ended up applying to were:
Proctor (where she is now)
Millbrook
Suffield Academy
Pomfret
Other schools considered that could be worth a look, but where she didnāt apply:
Tabor
Williston Northampton
Holderness
New Hampton
NMH
Berkshire
Mercersburg
St. Andrewās School
Millbrook was a NICE extremely friendly school in so many ways. (they have a ZOO). Taft also had a nice vibe but definitely more academically intense. Canterbury and Williston might also be good options- smaller but definitely friendly and personal. Canterbury is not often mentioned here and has some beautiful facilities.
The overall culture here is very intense when it comes to education generally and college admissions in particular. I think the international schools feel stuck in the middle between needing to provide a certain cache/brand while also wanting to counteract some of the intensity. So the teachers focus on social/emotional development and critical thinking and less on rote skills, since those are heavily emphasized in after school private tutoring/programs. I also think that kids who are not hyper motivated (and/or whose parents arenāt hypermotivated) can fall through the cracks. These are just my impressions and hypotheses. What is clear to us is that my son is academically behind where his older brothers, who went to public high school, were at his age.
My son also perceives himself as ānot smart,ā which I know is a pretty common emotional response among boys his age anyway. But it feels more pronounced and rigid in him. Heās surrounded by kids who have already learned material via private instruction, so he feels slow and afraid to ask questions. To be clear, the school isnāt terrible. I think he will probably be fine if he stays here, albeit a little underprepared academically and lacking in self-confidence. But life as a teenager here seems pretty un-fun. I want him to feel more empowered to explore interests and take risks. That is definitely not how I would describe the broader environment!
I have heard that both colleges and boarding schools give priority to ex-pats applying from overseas. I donāt know this for sureā¦ you may want to reach out to an American boarding school consultant for clarification. Instead of looking for āless academicā maybe change your lens and to look for ākinder and gentlerā. You may be surprised at what you find: Peddie in NJ, Dunn in CA, Webb in CA, George and Hill in PA, and St. Andrews in DE. Spend some time on Google. I bet youāll be happy with the results. Remember: Your son is already unique being an American applying from a school overseas. and yes you can reclass, but talk to a pro. I think he will be an amazing candidate! Good luck!
I donāt necessarily think itās priority per se, but I think that the schools appreciate the different experience that these students bring, the fact that they are generally committed to being at BS, and often that the employer will pick up the tab. It doesnāt hurt that ex pat kids are applying from all over the world and arenāt all in the same geographic bucket either. I suspect itās an advantage in many ways.
Some schools have developed relationships with certain employers (i.e., State Department) over the years or even ones near their headquarters as it is critical to these families that foreign assignments not disrupt their kidsā education, and they may work with them to accommodate a late application or mid-year move in a way they would not for you and me.
MiIlbrook is definitely a hidden gem