With only a day to visit town, we used this resurce quiet often and with satisfaction. It covers the touristy area, runs four times an hour, and cost $2 by trip. It stops close to the main attractions of the city, and it is good for a hop on hop off plan.
A great way to get around Philadelphia reasonably is to use the Philly Phlash. It's a purple trolley that runs throughout the center of Philadelphia, stopping at 20 strategic locations.
Each of these stops take you to or near major attractions and runs daily l0-6 p.m. from Mar 1.-November 30. *An all day family pass costs only $10!! Seniors ride free daily except from 4:30 p.m- 5:30 p.m.
If you use one of the EZ parking lots (see listing on www.gophila.com/phlash) you can redeem $1 off the cost of a day's parking. Maps are distributed on the Phlash, so we had no problem getting around to anything we wanted to see. The phlash leaves about every 12 minutes and tickets can be purchased at The Independence Visitor's Center at 6th and Market Street.
FYI: In 2007, the Phlash begins operating at the end of May. Individual passes are $1 for each time you board the trolley. (*The family pass for $10 is an all day ticket for two adults and two children, ages 6-17.)
To me, the best way to get around town is by the purple bus, Philadelphia's PHLASH. For the price of US$4 (all day pass), one get to see & stop at the major sights along its downtown loop with easy access to the city's most popular tourist attractions, hotels, City Hall & South Street. It is especially ideal for the first-time visitors.
PHLASH runs daily, every 10-15 mins. from 10 am to midnight. The entire loop takes about an hour & is a closed loop; riders can get on & off at any stop & know that they'll be returned to where they started. In fact, it's actually a guided tour in that the drivers do give a narrative of the major sights.
Official Site: http://www.phillyphlash.com.
Route Map: http://www.phillyphlash.com/map.html.