Airport Wireless has stores in several of the airports you mentioned. I bought a U.S simcard at one of their stores which had a SIM from "o2 Wireless". The card worked well, with no contract only top-up cards, but not needing it for data use, only voice, I can't reply to it's data availability. Good rates for calls, including internationally. Website for o2 Wireless is:
www.o2wirelessservice.com
Website for Airport Wireless is:
www.airportwireless.com
Their website has a listing of which U.S. airports have their stores and in which terminals they're located. You can email them your questions about a sim with data capabilities.
bj-21.