Both previous answers provide a good description of the areas. However if you must have sidewalks and curbing then you do not want Arborlea. If however you like an eclectic mix of housing with mature landscaping then you do not want Penn's Grant. Your best bet is to contact a local agent for an area tour.
We live and work in the Yardley area and can help you find a neighborhood that meets your astehtic.
Fran and Mark Redding
Prudential Fox & Roach, Realtors
1010 Stony Hill Road
Yardley, PA 19067
Penns Grant is newer, priced mainly in the high 2's, low 3's. More of a tract feel (because they're newer).
I think your family could be happy in either neighborhood. Both are very nice.
If you need more info, feel free to contact me directly @ firstname.lastname@example.org
Penns Grant = A little newer homes than Arborlea, tends to have younger families, located in Falls Twp.
Both go to the Pennsbury School District, even though they are in different townships.
Here is a list of homes currently for sale in both communities so you can take a look. You can also search the live MLS at my website http://www.kimberlyrock.com to view more properties.
Please let me know if you would like to discuss making an appointment to view any of these homes, I would be happy to help! I sold a home in Penns Grant last year to another young family with 2 newborn twin babies and they are very happy.
Keller Williams Langhorne PA