I lived in BCN for 4 months while finishing grad school and had the best time of my life. If you're looking for a great summer trip - PLEASE visit Barcelona. There is everything from the beach to great dining to fabulous shopping... the people are amazing, it's super easy to get around by bus or subway. Heck, because of all the transportation strikes, I walked practically everywhere (it's semi-relatively doable)... if you're wanting to visit more of Spain or Europe, that's a snap too but try to spend at least a week here because there is so much to see and do!
Quick Tips:
Visit everything Gaudi... he's the very famous architect that gave BCN it's look. He created parks, apartment buildings, you name it... just pick up a "Ruta Gaudi" at any Gaudi tourist location for entry coupons and a map on how to get around. Make sure you spend time at the beach... take in a quick meal at Quinze Nits; it's about for 3 courses - no kidding. Have a beer at La Oveja Negra and check out the great shops down Diagonal. You can find all these locations in any typical tourist book so I will spare you the details and directions. If you need a travel agent in a flash, your best bet is El Corte Ingles... you seriously can find everything here. Just watch your Spanish. In BCN the language is Catalan which is like a mix of French and Spanish with a lisp.Best Way To Get Around:
You can take a bus or the subway... it's just like NYC, so get a map. The one thing I did find is that the bus system isn't totally reliable. They were on strike more frequently than not when I lived there... though that might have changed. Cabs are find too - the usual price. But if you're looking to check out BCN and outlying cities, rental cars are really cheap if you can drive stick. If not ... learn.