Safeties are hard to identify and harder to love than super selectives, but they’re out there and your son will find them. I think the first question is still your original question: Are small LACs the right fit for your son? If yes, then the next question is: Should his safety school(s) be small LACs also? But you have to answer the first one first.
I would also try to sit down with your son’s adviser and get an understanding of why he thinks your son should consider LACs. Is it the small classes, the insular close knit communities, the dedicated faculty relationships, the continuing alumni/ae support? These are all good reasons to choose an LAC, but they may be more meaningful for one student than another.
Though schools like Williams/Amherst/Swarthmore/Pomona are highly selective they’re not quite as selective as Columbia and Brown and much less so than HYPSM. I think the kids who choose W/A/S/P based on ratings and prestige as second best to the Ivies that they didn’t get into are the ones who end up dissatisfied. If their real first choice is Brown or Columbia, they may be better off at Georgetown, JHU, Duke or CMU than at an LAC. (I’d also include Chicago, but it has become very selective in the past few years.)
So take it step by step. Use this trip to visit a few LACs get a feeling of where to go from here. Maybe he can do some more visiting over the summer after he narrows in on his priorities and wish list. Based on his profile, my vote would still be Williams and Wesleyan, but the Northeast is compact geographically and you should be able to fit in several.
Your son will be a strong contender at many schools. I would want to exploit the music aspect and submit a performance supplement even if he doesn’t plan to major in music. Music as an EC is more significant at some colleges than at others, though it’s always a positive. Performance opportunities for non-majors also vary widely.
Yes, that’s the end game: A high achieving, non-hooked applicant has to cast a wide net, especially if he’s a Whiteand middle class. If he includes reach/match/safety options in different sizes then the list expands exponentially. The good news is that need-based aid appears to be workable for your family, which makes the search for financial safeties less complex. Think of it as ever-narrowing concentric circles. You may start considering 35, visiting 25 and applying to 15+. The bull’s eye is the one he ends up attending.