Here are your choices (AFAIK):
a) AA via SJU (three or four days a week)
b) CO va EWR (one day a week)
c) CO via IAH (one or two days a week)
d) AA via MIA to CUR and then a $110 rt flight on Divi Divi to BON (7 days a week). Take the am flight to CUR and the pm flight to MIA
e) Delta via ATL (one day a week)
ReefDiva is correct about prices. Here is what I have found from SEA, from least expensive to most: d, a, c, b, e
Of course, from Sweden I would go to Amsterdam and then take the non-stop on KLM. While I don't suggest it, you can fly to AUA and go from there as well.