My spouse and I will be visiting Philadelphia soon. Are the neighborhoods between the Amtrak Station (30th Street), The Sofitel (South 17th Street), and the various museums such as the Barnes Foundation North of the Sofitel suitable and safe for walkers?
Safe in what way?
I'd say it is as safe as any North American city in downtown areas.
Take regular precautions, be mindful of your surroundings, keep bags closed, leave valuables at home or in hotel room.
I would walk from the hotel to the Barnes Foundation; but maybe not from the train station, especially with luggage as it does not look nice (safe, but not nice).