Well, I do hope you check back here.
I think that the decision should be at least partially emotional. You can consider, you are buying a commodity- an engineering degree. What is that worth? He will actually be fine probably anywhere to get that basic education. Then ask, what are the intangibles that are draws for him? Access to Silicon Valley Start-ups for internships? Hearing amazing speakers? Taking specific kinds of hands-on classes? Being able to be part of a co-op? Give each a weight, or more importantly a price tag.
I am in the camp that inspiration and imagination go a long way, and it is worth it to get that spark. It’s kind of like the MasterCard commercials (or is it Visa?). Some things are just priceless!
I personally would value a top tier school (and all that goes with it in terms of intensity of experience and overall inspiration value) at somewhere around 2 years starting salary premium over a “commodity” school. Others would value it at 0-1 year premium.
So, when you have figured out your personal value system, you are ready to rank schools in terms of “premium.”
Then, you are ready to find the money. Once you have dialed in your values, you can run NPCs, and determine what brand of “Champagne” you are likely going to be able to afford (or maybe you will find that you are on a Beer budget).
Your son will then have a fairly good idea of where he is likely to end up, and he can wait for the offers to arrive. More importantly, he will know why he chose the school he chose.
I hope this was helpful, because I do realize that I just described pretty much everything from his full-ride offer to about $30K/year, net. The point is, there are two reasons to go to school- one is for the commodity trade skill set; the other is for the experience and inspiration (how you will be in the world and how you will use the tools). I would pay a premium to amplify the learning in the latter area- the challenge is to quantify the premium you are willing to pay and to quantify the value the school is likely to deliver. For some, they either don’t value the latter aspect (they may believe it is intrinsic to the person and the school adds little), or feel it is worth a different premium. This is where you and your son can have the fruitful growth discussions- trying to grapple with this question.
This value system is so different for each family that it is worth having the explicit discussion (and difficult for good advice to come from a discussion board).
I do value undergraduate education, because I believe that is the (emotionally) formative time. Graduate school is professionally formative, but is really a relationship mostly within your lab, or maybe your department; but does not have as much of that broad explore-the-world feeling where one is seeking out inspiration.
By the way, congratulations on your son’s full ride and near-full-ride acceptances!
The best way not to go crazy over something is to assert some (feeling of) control and order over it. Use the time you are waiting for acceptances to help your son get to know himself and his value system better. It is easy to minimize cost. It is easy to de-value emotional experience. Help him to not do this, but rather to find a way to quantify intangibles and come up with a “best value” metric that embraces and does not run away from his personal, honest, values.