Any good, cheap places to park while touring the historic section of town?

Not that I know of. You might try the lot at the Holiday Inn, 4th and Arch. I think they're pretty reasonable. Otherwise, you'll probably pay about $20 (It's actually cheaper to park at a meter take your chances on a ticket, which is generally $15).

Better idea still:

Park near the Art Museum for free, walk up to its back entrance, then ride the Philly Flash into downtown. You'll save time, money, and aggravation.

www.phillyphlash.com/home.html

Re: the previous suggestion

Be forewarned that most streets near the Art Museum have now gone over to timed parking (one or two hours--not enough time to get to the historic area and back), largely because the residents were tired of people trying to park in their neighborhood for free!

To my knowledge there are 12 hr meters on the Benjamin Franklin Parkway, unless they have been changed. Be sure to bring quarters as they do not accept dimes or nickels. You can easily walk or take the Philly Phlash to other downtown attractions.

To the previous posters, i live in the art museum area and there are still some 12 hour meters available close to the ben franklin parkway. There are also free spots (not metered) along some of the numbered streets north of Spring Garden. (21st, 22nd for sure). Also, if you're going on a weekend almost all of the parking is free on Saturday and Sunday.
Philly Phlash is a great and cheap way to see the city.

Also, if you're determined to park in Olde City, there is a parking garage for the Ritz Movie Theater on Second street between Chestnut and Walnut that is fairly reasonable (bet. $8-10). Although I usually find some free spots by just driving around (3rd street is usually best). Like the Art Museum parking, street parking may be free on the weekends in that area.

Hope this helps!

I actually checked the meters on the Benjamin Franklin Parkway, and yes they are 12 hours, but you still have to feed them on Saturdays, Sundays, and Holidays. Beware, since people often assume that they don't need to pay on the weekend and then end up with a $25 ticket.