Italian Food---someone already said it and was dead-on...Ralph's on 9th & Catherine. No frills italian food...and it's awesome. If you're with a lot of people, you can do Maggiano's. It's not very authentic, but they have that Family Dining special, and you can eat for days there...we had a bachelor party almost eat them out of house and home because they just keep bringing more out until you're stuffed...I think it's in the 11th & Race area. Great bar there known as the Independence Brew Pub and is right there with the Reading Terminal Market...great place to walk around in. There's also a BYO called Mercato on 12th & Spruce...great italian/mediteranean food.
As for touristy stuff...there is the Phillies stadium. I don't care what the other person said, because the Phils are in contention for the Wild Card and are showing no signs of slowing down. They in NYC with the Mets right now, but I'm not sure when they're coming back. If you're in town 9/17, that's the Eagles' first regular season home game and you owe it to yourself to get to the tailgate. It's a 1pm game against the Giants and fans should be there by 7am, some drunk by 8am....this is all good unless you're a Giants' fan. If you are, DO NOT wear a jersey or tell a soul you are a NYG fan, and you'll be fine.
Check out... http://foobooz.com/ and
www.philadelphiamagazine.com for more food stuff as well as all of the newest places to drink. Check out www.philly2nite.com for more drink specials.
You can't miss the Art Museum even though the tight-wad hoity-toity's have the Rocky Statue in hiding and are trying to get it to NOT go back to the top of the steps. There is a bronze plaque in the ground with a pair of Converse All-Stars in it where Rocky stood though....amazing view from there. There's also a lot within healthy walking distance from there...
There's Boathouse Row (the infamous houses that are always lit up and featured on damn near every Philly postcard) and Kelly Drive...it's all on the opposite side of the Art Museum from the one where the steps are. It's a beautiful walk too. Across the Schuylkill River (pronounced skoo-kill) is the Philadelphia Zoo. I haven't been there in years, but it does have a new 'zoo-balloon' that floats up a couple of hundred feet...I'd imagine the view is amazing from there of the city.
You can walk down the Benjamin Franklin Parkway right into Center City too. Off to the right from here you'll see Philly's newest high-rise, the Comcast building. Here's the progress and some comparison...http://phillyskyline.com/bldgs/comcast/i2.htm
There are always the cheese-steak places too. If you're going to Pat's and/or Geno's, try to get drunk first. They're not really that good, but at 2am agfter all of the bars close, there's nothing better than one of those monsters. Be prepared...the lines get nuts. There's also Tony Luke's on Oregon Avenue in South Philly...you don't need to be drunk in order to eat their steaks, but their Roast Pork with sharp provolone and broccolli rahb is what they're known for...it's the best thing you'll ever eat. Grab me one if you go. There are steak places all over the city, and depending on who you ask, the one around the corner from them is always the best. You'll just have to try them all I guess.
Old City is nice during the day...plenty to look at, eat and drink, but at night is when it gets poppin. It's kind of a more dressy crowd, somewhat pompous even, but a good time. There's a bar for everyone down there. South Street can bring out some of the freaky freaks, but there's a lot of bars there too.
There's history crap.
And then there's always shopping on Walnut Street in Center City.
Shoot me an email if you're looking for more specific stuff...I've lived here for all of my life.