I was wondering if you could help me.

I'm trying to book an affordable one-way revenue or mileage flight from PMI/BCN to Boston on August 12th or maybe 11th 2012. I've been looking at all the possible options including routing through european gateway cities but not much luck. I have miles on BA/United/American. I'm wondering which combination of mileage tickets and $ makes most sense. Any help would be appreciated. Thank you.