Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.601 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
Note that for redemption purposes, BA Avios can provide excellent value for the OP's situation. BOS-SNN/DUB on EI costs only 12,500 Avios. Combine that with a cheap flight to EDI (or an Avios Reward Flight Saver redemption DUB-LON-EDI -- with or without a LON stopover -- for 4,500 Avios and relatively low fees), and you've got a great deal for a TATL flight.