AVP (Scranton) is the airport that gets the most use for Pocono race (including many of the private planes and the goodyear blimp). However, can I STRONGLY suggest you consider another track for your pilgrimage (and I say that as a MAJOR nascar fan) this is one of the hardest tracks to enjoy a race at. The track configuration and size are such that much of the race is in another county (literally) and you see very little of it. Pocono is pretty much my home track and I still stay home and watch the race because you see much more on tv than you ever see at that track). On the upside it is the track you are most likely to see a deer hit on however!!!!!! *smile*
Also be aware that the hotel situation at Pocono is HORRIBLE. There is one hotel near the track, most everything else is a schlep.