One of the best ways to take in the city is on a horse-drawn carriage ride. (Make sure you bring an apple for the horse.) The ride allows you to see everything the city has to offer, from the shops to the historical landmarks. The driver will also stop if you ask him, to let you get out and get a cheesesteak and eat it while you ride. Although there's no commentary as you ride, there are brochures available to tell you where you are and what you're seeing.
This was my favorite part of the city.