I know it has been a long time, but I havenīt forgotten you.
1._ Sopelana. Nice place. Right between Getxo and Plencia, on the coast (and more important, it has two tube stations, Larrabasterra and Sopelana). Lots of surfers (the two surf mecas are Mundaka and Sopelana), and a nice coast walk to Algorta. I think it could be a good idea. I donīt know about the place, but I could have a look one of these weekends when I go to the beach.
2._ Another suggestion. The other day we went for a walk in Portugalete, on the left bank of the river Nervion. We took the metro to Las Arenas (Areeta station), and from then we walked over and passed the river on the Hanging Bridge. We walked around, and then I saw something interesting. It was a new hostal, kind of a B&B, just 5 minutes walking from the bridge : http://www.gaztenet.com/hostalsantamaria/ It seems quite nice, so it might interest you.
Regards, Covadonga in Bilbao (Spain)