Flying into Boston, and based on the schools on your list I would think about visiting Northeastern and Tufts in the Boston Area.
FYI The Springfield Armory is worthwhile, but it's only a couple of hours visit at best.
Your drive will include a lot of toll roads including some cashless ones. Check with your rental company about toll payment. You may want to consider getting your own EZ Pass.
Parking on Cornell's Campus is very wonky. Check their web site and try to pre arrange.
If you are going to Penn, you should visit Drexel. They are next door to each other and Drexel would probably make a good safety school. Their co-op program is one of the best in the country (Northeastern's is also very good)
If he's still interested in Ursinus, It's not that far out of the way if you are driving from Lehigh to Phila.
I agree with the others that dumping the car and spending a couple of days in Phila. is worthwhile. Penn and Drexel are in an area called University City which is separated from Center City by the Schuylkill RIver. My recommendation is to stay in Center City and either walk or take the "El", the Market Frankford Line to Penn and Drexel. It's also an easy ride on the commuter rail to get to PHL. King of Prussia is ok, but the traffic can be bad.
Have a Pork and Broccoli Rabe sandwich at DaNicks in the Reding Terminal Market and top it off with Bassetts Ice cream there. Actually just have a meal or two in the Terminal Market. There's also a lot of history in Phila, so enjoy!