Book through the Sesame site and get a hotel package.
I reccommend Marriott Residence Inn. All hotels nearby are budget hotels but with this one you get a kitchenette and a separate bedroom which as we all know helps when you travel with kids.
There is a van to take you back and forth to the park, it is a 7 min ride MAX. There is also a super bargain Marriott right across the street (I think Spring hill suites). These are not suites and not worth it. We did this last time and though we could walk across the street we sorely missed the space in the residence inn.
Also thanks to google I found this site for you
http://www.frugalphillymom.com/where-to-find-discount-tickets-to-sesame-place/