You may want to explore the Philadelphia forums on tripadvisor.com -- they're a lot more active in city-specific issues. I'd also check the city's own website, where you can find out about exhibits and events -- for instance, if you're into art, the Phila Museum of Art (a gorgeous place you'd want to visit anyway, if just for the great vistas from its steps) will be having a big Andrew Wyeth retrospective until July. It's the 5th largest city in the US, so there is a TON to do, depending on your interests. The one must-do is a tour of Independence Hall, where it all started - log onto the website and reserve a (free) ticket for the date you'll be there. When the guide points out Washington's chair and talk about Franklin's comment about the rising sun, it brings a tear to my liberal patriotic Democratic eye every time! Also, Google "Dream Garden" - a gorgeous Tiffany-Parrish glass mural in the lobby of an office building right off Independence Hall - a nice place to stop and rest your feet!

You don't want to cram Lancaster and Gettyberg into one day - Gettysburg really needs deserves a full day or two itself. I'd splurge and get a registered guide to ride around with you, at very least, be sure to climb and explore Little Roundtop, and walk the length of Pickett's charge, then spend the evening at one of the nice taverns in town for dinner. If you read "The Killer Angels" or the "The Stars in Their Courses" first, or rent/download the Gettysburg episode of Ken Burns' "The Civil War", it will REALLY add to your appreciation of your visit. The hotels there are pretty reasonable - one or two are almost ON the battlefield.

What you might want to do is reserve a full day & evening for Gettysburg, then drive through Lancaster on the way back to Phila, with a stop in Valley Forge (all in a straight line heading back on the Turnpike). Well worth seeing for its importance to our country's battle for independence, but unlike Gettysberg, Valley Forge is quieter, and demands a LOT less time for a visit (you can see what you want to see in an hour or two). If you're a shopper, you may want to spend that evening right there, and visit one of the country's largest and most upscale malls. At least for now, PA doesn't tax clothing purchases, so a visit to the King of Prussa Mall (Bloomingdales, Macy's, Neimann-Marcus, Nordstrom, plus a lot of upscale mens & womens boutiques) next to Valley Forge might be in order. Otherwise, back to the city, where you'll be more likely to get a great non-chain-restaurant dinner. Whatever you do while you're in Philadelphia - NO MEALS AT CHAINS ALLOWED.

One last caveat about Philadelphia. Because of a restaurant boom in a city with a limited supply of liquor licenses, many of the best-priced and most interesting new places are BYOB with no corkage fee. Which means you track down a state Liquor Store on the web, go there and buy your wine, then bring it to the restaurant, and save a lot of $$$. A headache for the out-of-towner, but a blessing to financially strapped locals who like wine with their meals. (Most places in Gettysbg and K of P DO have liquor licenses, however -- this applies mostly in the city itself)

Enjoy, but be SURE to get that Gettysburg sidetrip in -- well worth it!