To get Philadelphia stations from Douglassville you're likely need a large UHF/VHF-Hi/VHF-Lo antenna (or multiple antennas covering all three bands), no rotator. Put it on the roof, point it towards Roxborough, and barring local terrain obstacles, you're golden.
If you'd rather have Allentown, that's probably doable too. If you want them both it's a pain involving either a rotator or multiple antennas. Pointed towards Philadelphia you can probably pick up WTVE-Reading from the back of most antennas; I don't know about any of the other stations west and north.
Oh, yeah, and overkill on the antenna is unlikely to hurt, except for a few dollars of one-time cost.