M.N.
Hi A.! Welcome to the area! We actually moved here last summer and I have two, one just older than two and one that is 8 months too. I actually have been working on a site, a blog for right now with parks and activities in this area for moms and kids or families to do because I could only find scattered info. I do not have a ton on the NJ side yet, but Mercer Park is great and my husband works in Hopewell so we have been venturing over there a bit more.
You can see the ones I have done so far at http://www.downinphilly.com/. It was just difficult to find much information about most of the parks so I hope it helps a bit:). Feel free to email me if you need any help finding them or you find any great ideas too:).