Since we've gotten so many Lowes/Home Depots by me in NEPA any of the ones I could have recommended years ago are long since gone, including the ones I used to go to in north jersey. The few that are left that I know of it seems to me, but I could be wrong, that they get their plants shipped in just like the box stores. It appears to me to be the same stuff everywhere. I don't know of any place that still has greenhouses with seedlings they started or unusual items anymore. All of the places I've gone to have even less stock this year than last year which was pretty slim. The economy is definately affecting them too.
I know these aren't general gardening retailers and they are both in SEPA, they honestly aren't far at all and are exceptional places, but I can at least recommend them!
Parkside Orchids in Ottsville http://www.parksideorchids.com/ Has a huge selection, the orchid forum has several reviews of their fest I went to last weekend.
Violet Gallery in York Springs http://www.violetgallery.com/ I have not been to, am planning to this summer, but it has been highly recommended to me several times.

I too would be interested in finding any other places in NEPA that sell a variety of plants or that specialize and come recommended :)