Yeah it is always a problem from the US. The airports that are nearest the Camino don't have international flights. I would say get the cheapest flight to Spain which would likely be Madrid and get the bus or train to Pamplona.
From there you can get the bus to Roncesvalles or a train to Bayonne and another local train to St Jean.
Also if you are money poor and time rich, I was when I first went, it might be worth while checking out the flights to Paris and getting an overnight train from there to Bayonne - booked well in advance the train can be as low as 50 or 60 euro.
Then getting home - maybe a flight from Santiago to London with Ryanair - very cheap. The more time you have the cheaper it can be.
Hope some of this helps.