No-one replied to this yet, but you've got several comments on your Brown thread. Here are some thoughts about this.
Has your son emailed Brown to express interest? (and Swarthmore, for that matter, and 10-15 other schools). The best thing would be to do so, and if they reply, to ask THEM where they will be, and what they want to see.
We found that Ivies send coaches to the major 17U tournaments to watch players, that includes WWBA but also others. If they aren't at WWBA, they have access to the data through Diamondkast, so they can see what happened (and yes, some did look - son's velo was not what they wanted, and they saw that). Also, if you go to WWBA, you are showing that you have played against high-level competition. HA showcases, not so much - but, measurements like velo, 60-time, EV are, of course, still valid.
Son only went to one HA showcase, Headfirst Long Island in August. It worked out great for him, because he had a great showcase. You could say he was prepared for it by a summer of high-level tournaments; also, these coaches talk to each other, so exposure to one might mean exposure to others also. It's really impossible to measure how each thing my son did fit together to produce the result that it did, but it worked.
Final thought: take video of his high-school games pitching, send that out also.