Agree with leading with academics. Here though there is a bit of a decision tree having to do with academics, cost and opportunities.
If IB/consulting is a long term career path, there are a few highly rejective schools that are feeders (Ivies, most NESCAC’s, Swat, Claremont/McKenna/Pomona). Full pay at $360k may be worth it if the first job coming out is $125k. Probably not worth it if his interest lies elsewhere unless you feel that it is enough of a unique experience to pay for it and you can afford it.
In terms of academics. Fit in terms of majors is important. However, what many people under-value is the quality of classmates. Kids learn so much from their peers, and competition can be very beneficial. Both S and D went to highly rejective schools, and it was humbling to not be the smartest kid in the class like in HS, but for them it was motivating. So it is a bit of question of what is more suitable for your son. Some thrive being the big fish in a small pond, others need to be thrown in the deep end.