get from Princeton University to Philadelphia 30th St Station
 

College student making biweekly trips on Saturdays to Philadelphia for the orchestra.

If you are asking for options, I can think of 3: 1) Get a zip car and drive; 2) take the Dinky to Princeton Junction, then Amtrak to 30th Street; or NJT to Trenton, then change to Septa.

It looks as if the best bet is to get to Trenton from Princeton and take the Trenton/Philadelphia Septa regional rail train; looks to be at least 2 hours each way if using public transportation. Is it possible to drive into Trenton Transit Center and take the train from there?

The cheaper option is to take NJ Transit and then to change to SEPTA. That works fine from Princeton and should take about 90 minutes if you plan your trip well. You don't really save that much time driving to Trenton. It's just about 15 or 20 minutes from Princeton by train (2 stops).

There's an NJ Transit bus (#606) that runs from Princeton to Hamilton Marketplace with a stop at the Trenton Transit Center. It's about a 45 minute ride; service to Trenton begins at about 7:30 am from Palmer Square/Nassau St and last bus from Trenton to Princeton is at about midnight.

From Trenton Transit Center, you can get the SEPTA to Suburban Station in Philadelphia. From there, it's about 10 -15 minute walk to the Kimmel Center, or you can take the Broad St. Line subway to the Walnut-Locust exit.

The NJ Transit train option to Trenton (Princeton to Princeton Junction, PJ to Trenton) might be quicker, but only if timed exactly right. Note that the dinky from Princeton to PJ is generally optimized to trains going from Trenton to NYC, not necessarily in the opposite direction.

If time is more important than money, driving would probably be a better option. It's about 1 hour and 15 minutes driving from the Princeton area to Center City.