Keystone Service Amtrak trains to Philly and New York depart Harrisburg on the hour. The former PRR station is located at 4th & Chestnut Streets, south of the Capitol. It's been restored and it really looks good. The first GG-1 to depart Harrisburg with a passenger train as well as a restored PRR wooden caboose is spotted by a platform. Use the parking garage across the street from the station. The ride to Philly takes about 90 minutes.
From 30th Street Station in Philly, take any SEPTA train to Center City (free for Amtrak passengers). Get off at the second stop, Market Street East and Convention Center, the former Reading Terminal at 12th & Market. Ride two escalators up to the Convention floor. The largest single-span train shed remaining in North America will unfold overhead. Then go back down one flight and enjoy lunch or dinner in Reading Terminal Market (www.readingterminalmarket.org). Take a cab or walk along Benjamin Franklin Parkway to The Franklin Institute (www.fi.edu). Enjoy a cab ride in Baldwin 3-cylinder compound 4-10-2 No. 60000 in The Train Factory (formerly Railroad Hall). Fels Planetarium and an IMAX theatre there put on good shows, too.
Across from City Hall is Macy's (formerly John Wanamaker's), a Philadelphia landmark. Speaking from experience, I know your wife will enjoy shopping there. A SEPTA Museum is located at 1234 Market Street. Independence Mall is located a few blocks east. Returning to 30th Street Station from Market Street East or Suburban Station (by City Hall), take any SEPTA train leaving from Track 3 or Track 4.
Farther afield, NJ Transit runs trains between 30th Street Station and Atlantic City.
Riding a Keystone Service train to New York City provides access to an F subway train to [the late Peter] Bianco's Trainworld at 751 McDonald Avenue (Get off at Ditmas Avenue). The subway becomes an elevated ("el") when it leaves Manhattan and enters Brooklyn. That would be a long day, but I'll suggest it as an option. If not this Thursday, maybe another time.
We salute you, sir.