Are there LACs I should add to son's list?

Depends on your definition of substantial. My understanding is that Kenyon tends to offer mostly around $15k. Grinnell and Oberlin may give more to the student they truly, deeply, want to attend, and those awards are much rarer. They typical award is again, closer to $15k. Real money for the full pay family who wants to shave something off that $68k list price.