If your son is a strong candidate for Swat & WUSTL he has lots of possibilities! Important factors:
$$: avoid debt at undergraduate
Plan B: the conversion ratio of students who start college in the pre-med track v the ones who actually go to med school is terrible. The school should have other aspects that he likes as well, just in case.
Star power: many colleges have committees that write all the LoRs for their med school applicants. If your son is a star at college that will come across in the committee letter / any LoRs. Remember that the first cut is on numbers (GPA & GMAT) and that with the exception of a few outliers, the prestige of the college is not a factor (Harvard & Yale do seem to favor their own & each other’s undergrads).
So, a lot comes down to where your son will thrive. Is he the kind of competitive that is happiest testing himself against the best? A more introverted soul who might need a supportive environment to keep developing the social skills that will be important? A hail-fellow well met sort of fellow, for whom social time is the oxygen that keeps his academic flame going?