Hi
Yes, Barcelona is a great place, cool, buzzy, tonnes going on, lots of interesting districts, english is spoken in quite a few places, is on the high speed rail network and has a well connected international airport. But, as another has said, people can be a bit more miserable, a bit harder, than the spanish norm. And property prices are crazy high.
Alternatives that spring to my mind:
Madrid: Property is as crazy as Barcelona and the climate is tougher (hotter in summer, colder in winter) but on balance, probably a better place to live. There is more there, its more international, less swamped with tourist, the people are a bit happier and it´s got that capital city buzz. A complex and diverse place.
Valencia: Spain's third city is often compared to Barcelona. It is where I live. Both are one the coast, both have an old town, both are modern cities. Valencia is much smaller than Barcelona / Madrid and its airport is not so well connected (but still not bad). It has a nice climate, never seeing frost and never getting crushingly hot (well, there are about 3 weeks a year where the locals flee for the mountains which surround the place). Its very cheap, one of the cheapest spanish cities, with housing a third the cost of the big two and menu del dias going for ten euros. It has a good public transport infrastructure and is small and flat enough to make walking/cycling a viable way of getting about. English is not common. Everyone seems ridiculously chilled and happy.
Seville: Lots of people like Seville, with its gardens, old town, and Andalusian culture. I do not know it well. We were put off by the crushingly hot summers. Its beautiful, and there is lots of stunning countryside to visit near by.
Zaragoza: Spain's 5th city is often overlooked and I do not know why. 2 cathedrals, loads of things to do and see, proud locals, close to the Pyrenees, a high speed train ride away from Barcelona and Madrid. 2 hour drive to Valencia. But it does get really hot in summer (like 45C), and cold in winter. It's a tougher, more sensible, more northern sort of place than Valencia.
So that is the big 5. Some random smaller places:
I like Valladolid. Capital of its region, there is a nice sense of community. Close to Madrid and linked by high speed rail. People seemed happy. No one spoke english. Its the only place I in spain where have been stared at in open-mouthed amazement for speaking english. If this sort of local place appeals, consider Ciudad Real as well.
Alicante is nice, facing the sea surrounded by mountains. Lots of expats live there and the locals are used to foreigners. It can be expensive, especially if you try to live in one of the surrounding coastal villages where norther europeans push up house prices.
Bilbao is a good place. But like Zaragoza, people are harder, more businesslike than the south of Spain. But be aware that the northern coast is wet (you can get rain all year round, so nothing like Valencia's 300 days of sun a year). It snows in the winter. Everything is green.
Cadiz is small and beautiful, and being surrounded by water on all sides, a lot cooler than the rest of the south coast. Nice vibe when I was there but I have not been there at peak tourist season.