@Veryapparent Understood, and agreed about kids being able to get a feel for fit! When I think of the reasons my LAC kid passed on some schools – sometimes, they were “markers” for bigger considerations and sometimes, they were just silly, but maybe as good a reason as any to shorten the list. Like at Conn Coll where he didn’t like that the athletic training facilities were reached by a pedestrian bridge over a busy road, but the match field for his sport, as a prospective recruit, was in the middle of the academic quad. Really, that’s why it comes off the list? Okay . . . .
I think your two strongest contenders are St.Olaf and Denison.
Denison’s writing has become excellent, perhaps due to a competition with Kenyon; their non fiction writing program in particular is great. Its climate is milder than Minnesota’s! 
Swimming is very strong and it has Greek life.
St Olaf offers strong support for English majors’ study abroad including for their January term and for a semester or full year. The Great Conversation (great books program) but also the American conversation would be of particular interest in grouping students who share similar interests in reading, writing, and talking about what they read and write. That weather can be harsh and there’s no Greek life. Music is very strong.
Re: 529’s.
Correct that is they are not used for education, you do need to pay taxes on the appreciation of the asset not used for education, not the asset itself. So this will depend on how much it appreciated before it was spent. Might be de minimus, might be larger number, but not a make or break at all and still very valuable.
Whatever school you nudge your son towards, at this point I would leave money out of it except to tell him that if he spends less now, there may be funds available for grad school later. It appears that you have told him you can afford all the schools, and you have said you can. But, why spend the extra money when your son can get a great education at any of these schools. Find great things about the less expensive schools and try to nudge him in that direction.
I’m not a big one on nudging. If you truly don’t want to spend the money, which is quite reasonable, you probably should have said that earlier, but if you didn’t, say it now. If you are going to pay the tuition to his number one choice no matter what, then step back and let him choose. It’s the biggest decision of his short life and he should be free to make it within clear parameters. I know this might not apply to the OP, but I just couldn’t stop myself from saying it.
@chippedtoof
My daughter would absolutely pick Kenyon again. She has many friends from both coasts. The student body seems, if anything, a little more geographically diverse (in terms of U.S. geography) than many of the northeastern LACs she considered. There is a large contingent of students from southern California. I would say the same for New York, Washington D.C. and Chicago. As a New Englander, this is an aspect of Kenyon that she particularly appreciates.
We just came back from a visit to Whitman. I was very impressed by how clean the campus looks and how everything was so convenient for a student. The support seems to be first rate. My son is being recruited heavily by the golf coach. We are also from Northern California, and despite the long drive for me to go there, I would not mind him attending because I feel that he would get a more supportive education and I could depend on the coach to help us get him through the college experience especially since the coach’s wife is a professor there in his major. It is a beautiful area and campus, people are very friendly.