IMO, it really depends on which schools he is interested in. It’s possible to just show up at HF and make connections, but a much more effective strategy is to target specific schools and show up having contacted those coaches beforehand. Those coaches will be much more likely to search you out and evaluate you for their programs. Look at the confirmed coached at each HF session. You’ll find some schools on the Northeast list that aren’t at the West Coast sessions, and vise versa. If your son’s list includes Northeast schools, he could attend the Long Island camp, and visit schools on the same trip.
I’m also of the opinion that you don’t need showcases if you have a well vetted list of schools. Attending camps at your targeted schools is a much better way to get recruited, assuming you’re a decent candidate for the school.