S1 also liked the Trimester system once he thought about it. He didn’t like the mandatory foreign language requirement, though. Don’t know if Amherst has that.
Amherst’s open curriculum, by definition, does not have such a requirement.
There are ways to get out of the foreign language requirement at Carleton:
https://apps.carleton.edu/handbook/academics/?policy_id=21481
[Start - defense of foreign language requirement]
That said, my personal opinion is that every American kid SHOULD be required to develop a minimum level of fluency in a second language, whether they like it or not (and I know many college students complain about the requirement). Many top LACs, most Ivy League colleges, and Stanford agree.
[End - defense of foreign language requirement]
I agree @bobshaw. Though the quickest way to do it is to spend time studying it…abroad. IMO.
Thanks for the comments everyone! They were very helpful. A lot to think about, some things favoring one school, some the other. In a way, I’m glad it was my son making the decision and not me.
We found @Pasadenadad’s comment very thought-provoking. I mean, we’re in Illinois, how can we go with a school with Michigan colors!
Anyway, I’d say that overall my son just felt that he’d be more comfortable at Amherst, that it was more the kind of place he wanted to be at. So Amherst it is.
So we’re all set now … unless we get a call from Williams this week …
Congratulations csdad2 - and as you will soon find, that Williams joke isn’t funny 
Congratulations to your son! Glad to hear he knows where he’ll be more comfortable and selected accordingly. And he gets to experience New England.
Williams? Pffffttt… You have Amherst. Why would you give that up for 4 years in the sticks? 
^ My theory? USNWR has Williams #1 and Amherst #2. College by numbers… 8-|
Or maybe the OP just prefers Williams? It happens, you know.
People who think I was serious don’t understand the friendly but deep rivalry between Amherst and Williams. I have nothing but respect for Williams.
Everybody’s using smileys :-).
I will say that my son is likely aware of the rankings … but then I can’t really disagree with his decisions or preferences, or the reasoning behind them.
And we are aware of the rivalry between Amherst and Williams. It is basically that he (and in fact, we) has a preference for Williams. It has most of the advantages that Amherst has, plus it’s clearly better in Physics (and Math). And we really did like the location – it felt like a Swiss mountain town. (It is behind Amherst in a few ways, like an even greater emphasis on sports and less diversity.)
But now I’ve probably jinxed things sufficiently that we won’t have to worry about this …