Are you ready for the time of your life? If so, go to Bilbao! I studied abroad there Spring semester (January-May) of 2015. I lived in Algorta, Getxo, and studied at Universidad Del Pais Vasco in Bilbao. The schooling was definitely challenging because I took 5 classes, 3 business, 1 GE, and 1 Spanish. One of my biggest suggestions is to take the "Unique Basque Language and Culture" class. It was by far the best decision I made. We were exposed to so much culture, learned the language of the locals, tried amazing cuisine, and took 7 field trips in the Basque Country. The teachers were great and the USAC staff were very welcoming and helpful.
The other students in my program became some of my closest friends and I still see them at least once a year. I got to travel a lot while abroad, but I didn't start my traveling until a few weeks in. I suggest doing this so that you give yourself a chance to adjust to life there and make it feel like home before venturing out to new countries.
There are tons of activities to do around the city, the Guggenheim Museum, Casco Viejo, and Athletic Bilbao (the soccer team). Tickets aren't too expensive, and it's a great experience, I highly suggest going. I lived in an apartment with two Americans in my program and I loved it. I knew a lot of people who stayed with host families and had great experiences as well. I lived only a few blocks from the beach and all apartments are walking distance from at least one grocery store. Everything else was easily accessible by the Metro, which is cheap, efficient, and easy to use.
I could go on and on about my experiences and how much I loved it, but I'll let you experience it for yourself! If you have any questions please feel free to reach out to me!