I'm also Philly-based, and, while it's not the world's greatest place to live if you want to get out, there are a bunch of places nearby, especially if you're willing to expand the radius to about 4 hours. The Black Forest Trail (Slate Run, PA) is a really nice 43-ish mile loop that has a pretty decent amount of elevation gain and loss but some really gorgeous vistas. (It's in/around the Pine Creek Gorge, which also has a bunch of other trails near it, including the West Rim Trail.)Both of those are about 4 hours away from Philly.
Another possibility to look into is the Pinchot Trail- I don't remember where it is in the state, but, from earlier planning, I believe that it's about 2-ish hours away from Philly. I haven't done it myself, but it's not known as a super strenuous trail (~22 miles or so), which might also fit in a bit with some of the goals in your other thread.
Also a possibility is Harriman/Bear Mountain State Parks in NY. I haven't hiked them (the time I went up, snow coverage was WAY higher than I had expected or planned for, so I bailed and went to go sleep inside instead), but they're very popular areas and the parks were very nice when I was there.
All that said, I will say that my big stomping ground is Shenandoah NP, which is a bit further away than what you seem to be looking for. The combination of scenery and route intel (their website has a ton of great information on routes, etc.) usually can't be beat for me, and it ends up being a very easy choice to fall back on. Since you said you come from MD, I wouldn't be surprised to hear that you're familiar with the area, but it's really not all that much of a haul from Philly. I usually do about 4.5 hours (renting a car at the airport) in the mornings heading down, with things being a bit worse on the way back. My usual trip has me leaving the city at 6:30-7am, getting to the park by 11-11:30, and on trail by noon before knocking out 25-30 miles over 2 days and being back in the car by mid-afternoon the next day. It ends up being a pretty robust weekend, but it's pretty doable if you don't mind combining a decent amount of hiking with ~10 hours of driving over a weekend.