The ones around here (Scranton area) are beat. There's one in Dickson City at the drive-in theater, and an indoor one in Eynon at the old Sugermans. It's usually old junk, household goods that were probably stolen off a dock in NYC, and crafts. I've been to the Saylorsburg one though, many years ago, and it was nice.
there are a few outside new hope on the jersey side that are pretty good--the golden nugget and another one whose name escapes me. lots of antiques and oddities, a little pricey, though, at least for me.
there are also a couple out near lancaster that happen once or twice a year and are usually a treasure-trove of goodies. way back when, before kids, my partner and i would hit up a few sales that way and scored somepretty cool stuff. we found out about them through a now-defunct website that listed flea markets, so i can't help out any more than that, but maybe someone from the area will know what i'm talking about.
Roots Market in Lancaster - I think there may be a website somewhere - it has like 2 or 3 huge indoor markets that are mainly for food, then outside is a huge flea market, food stands and some cool Guatamalean stuff, some antique dealers too. It's on every Tuesday and the first Sat. of the month. You can come hang out with me Lizzo!