6:30 should be fine.
I thought the airports would be insane the day after the most recent terrorist threat (my timing for these things is impeccable), but it wasn't that bad.
For those taking public transport or a cab/shuttle who don't want to have to go back to the hotel for your stuff, they give you full sized lockers with plenty of space for a small carryon (a soft bag will fit easier than the rolling kind), and for those with cars, there is ample parking right outside the door. You'll be in the car and on the road by 3:15.
If anyone plans on taking Septa (local train/subway), I'd be happy to give you some pointers. It was easy and cheap, if not the fastest (took about 80 minutes).