Barcelona is the Spanish city you probably hear the most about, but I’ll make the case here why you should go to Valencia instead.
First of all, Valencia is such a better value…
I spent about three weeks in Barcelona, and Valencia seems to have everything that Barcelona does at about half to a third of the cost. In Barcelona, a very simple flatshare in a kind of cool neighborhood costs 31 Euros a night, and a shitty hostel costs $22 a night, whereas in Valencia, I found that not awful private room flatshares via Airbnb cost $10-$15.
In general, the wifi in Barcelona is quite mediocre; the speed and reliability are so wanting that it negatively affected my productivity during the time I spent there. Disappointingly, there’s just a single real digital nomad-friendly cafe in Barcelona. In contrast, the wifi in Valencia is muy buen! At cafes, restaurants, hostels, and Airbnb apartments, I consistently found the +20MB up/down connection that I need to do work.
If you want to go shopping at a Prada store, Barcelona’s the city for you, but Valencia is overall a whole lot better value for nomadic seducers.