Thanks to my oldest child turning 13, we are now a family of 3 "adults" and 2 "kids" when it comes to paying admission, so the total price for the 5 of us at the Franklin Institute would have been $69.50, while the Academy would have set us back another $56. With our membership card, it was, well priceless (and free).
We also took advantage of a family pass from our local regional rail line, SEPTA. We were able to get into and out of the city for only $28 for the 5 of us. We will definitely use that again-next time we will do the historic district-when it's a little cooler in the fall.