I rarely go on a weekend vacation to another country (I’d want to see as much as possible but two days aren’t enough), though if you choose one town, you might be able to get the most out of your vacation. I was in Barcelona for a week. Awesome city, lots to see. There we rent a scooter from https://vesping.com and just went to the neighbouring towns like Rupit, Besalu and Girona. You can spend there a day or two but that’s going to be an exciting journey. Also, if you are in Catalonia just for the weekends, you can go on cava with tapas tours or visit Montserat. Actually, in Spain, especially in the southern and eastern parts there are lots of nice places of hiking.