You're DUB-MAD-BCN trip is a good one, which you could combine with a very cheap MAD-FRA RT on LA which nets your additional 30SC. I did this last year, and the LA flights in Q class cost me about £65 return all in. In theory it requires an overnight in FRA, but as you can print your own boarding passes, there's nothing to stop getting off the plane and then getting straight back on (aside from the odd look you may get from the crew).

I usually use the booking engine on aa.com which can sometimes give more interesting routings on IB flights.

BA still have a number of very reasonable CE fares out of LGW, mainly to places like GOA, PSA and FCO. MA have been advertising LGW-BUD RT for as low as £80 recently, so that might be a better bet than from DUB. It still earns 30SC in the cheap fare buckets.

Hope this helps. Good luck!