I live in Bucks County (northeast of the city). There are a variety of low income towns as well as some slightly ritzier areas the further north you go. (I live in the southern tip, not ragging on any it.)

It's not the cheapest county to live in, but it's enough outside the city yet close to the city to meet your needs.

If I were in my 30s and looking to rent, I might try Newtown or Yardley first.