Phillies tickets have actually been at or near sellouts so far. Of course, that's because of the new-stadium buzz. During the summer months you should have no problems getting tickets. I'd probably look to do so a few weeks in advance just to be sure tho.
I was going to recommend the art museum or penn's archeological museum, but I'm not sure that's really appealing to the 4 year old
gaither's definitely right on the franklin museum. That will have a little something for everyone.
Been awhile since I was at the Zoo, not sure exactly what it has in regards for kids museums. I'm sure it has something, kids are one of the biggest draws there. And It's cheap, and real close to the franklin institute.
You could probably spend a day just down in the historical district there's so much. From the Liberty Bell, to Independence Hall, to the house where Jefferson wrote the constitution, the 2nd national bank and so on.
I'll try to think of some other things.
