If he has any interest whatsoever in engineering, it’s best to start in engineering. It’s much easier to switch out of engineering than it is to switch in. That will narrow his options down to about 450 schools, most of them not SLACs.
If that’s not his thing, then he really has a plethora to choose from.
I realize that you asked about flagships, but you’ve mentioned SLACs too. Has he visited any schools? Typically, but not always, students find an affinity with either larger or smaller schools, but not both. That’s not always the case. It certainly wasn’t for our son who applied to schools as small as 5000 and as large as 32,000.
If he can tour say UCLA, CSULB, and LMU or the Claremont Consortium if you’re near LA, or Cal and Santa Clara if your in the Bay, that should give him some idea. It doesn’t matter if he’d be competitive. It’s about figuring out if a size “feels right.”
Big or small, there are all sorts of great options across the Midwest that aren’t necessarily on the radars of your average CC family where a student could get a great education and have a fun time.
Kansas and Iowa were the schools my classmates would leave Missouri for. Those who stayed at Mizzou though did fine. One of my fraternity brothers is a Fortune 500 President. My niece went to Iowa from Missouri and is in medical school now.
Grinnell, Kenyon, Denison, Berea, Mcalester and Beloit, to name but a few, are all worth a look.
So, yes, there are LOTS of large, medium and small schools that are semi off the radar, many where merit money will be generous, that could be candidates. It’s really a matter of narrowing the focus.
Our son left Oregon for a OOS public. He wanted a strong engineering program, with small classes, that started in major, featured early application of theory and was sunny. He chose Cal Poly (BS/MS ME). Oregon State at the time was none of those things. One of his HS classmates attended OSU, and then did his MS at MIT. They both have very successful careers.
That’s a long way of saying that an individual’s success is largely in their hands and not determined by the name on the undergraduate paper.
Best of luck. You’re asking great questions.
As as side note, Oregon State, Penn State and Hawaii, are the only universities to hold all four grant designations, Land, Sea, Space and Sun.