If you can take a trip down to Valencia and check out the aquarium there as well. Spectacular! My wife and I found it to be well worth the trip down from Barcelona. Go early though. We went at opening hours and had to be chased out by the staff at closing.
Wish I could go to Valencia. I'm here for work and only have 2 days to site see. I have traveled to a lot of European cities and Barcelona is now near the top of the list.