Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
"My first choice would be EWR-BOS on UA that night, followed by LGA/JFK-BOS on US/AA the next morning, followed by EWR-PHL-BOS the next morning."
Why not just forego EWR-PHL-BOS entirely, and book LGA-BOS in the first instance? With rail transportation, you should be able to get from EWR or downtown Newark to LGA in less than 90 minutes, and then it's just an easy nonstop on the either the DL or US Shuttle to BOS.