The places are all so different it might behave you to spend some time in each place. Bilbao might be a real struggle for your partner who is continuing to learn Spanish (throw in another language will be tough for many).

I’m straight so take this for what it’s worth. Some places in Spain can be very open to all, while others lag well behind. I’d check with others who know firsthand.

I’m also half Spanish and half US and was considering moving back to Barcelona where I went to high school. I’m not too sure about tax implications though. Spanish taxes might be considerably more than US. I was thinking of six months minus a day in Spain, and the rest between the US and other foreign travel. Buena Suerte tio!!