How much are round trip tickets. Getting on at Thorndale and getting off at 30th St philly I'll have 2 teens and one 6 yr old and one 9 yr old. Is there any price difference with ages?

Yes, its 15 per person for round trip between thorndale and philly 30st station. Family pass is the best choice I would say. To answer second question, I think there is a reduced ticket price for senior persons. You can also try Amtrack Express from Downingtown station for $16 round trip if you want to save time.

I believe round trip tickets are around $15 per person from Thorndale to 30th St. If you are going to Philly and back the same day they offer something called a Family Independence pass that might work for you. It covers 5 people on 10 trips on any transit for the day for $30. Here is some info from SEPTA's site: "The Independence Pass is ideal for individuals or families looking for the independence of convenient, economical travel on SEPTA services (pass valid for 10 trips). Occasional riders, visitors and families can travel on SEPTA to restaurants, shopping, casinos, sporting events and other attractions in the Greater Philadelphia region. Prices for the pass are $13.00 for an individual pass and $30.00 for the family pass. One family of up to five people traveling together may use one pass, however one person, but no more than two, must be 18 years of age or older."