Two days to see things from Barcelona?

I would recommend the tour of the Catalan Concert Hall also known as the Palau de la Musica Catalana. Plan an hour or so in advance or buy your ticket for the English tour and return at the appointed time. It is truly a work of art. Photos are not allowed. I would also recommend Sagrada Familia and Parc Guell for a nice relaxing hike. I went to the Picasso Museum but would spend time elsewhere unless you are a real fan of Picasso. The Cathederal area is very nice and there is a very nice restaurant nearby called La Locanda which I would recommend. It is behind the Hotel Colon and a good value. Watch for pickpockets..especially if you are at a sidewalk cafe setting near bushes. You might also consider Montserrat for a day trip.

If you are going in the summer, consider traveling to Stiges, about 1 hour south of Barcelona on the coast. Great beachy town!

What do you like to do? There's Las Ramblas, all the Gaudi/Modernisme stuff, The Barri Gothic, Picasso museum/sites and more. You can cram as little or as much in to two days as you'd like.

I'd poke on the way to Barcelona and spend a few hours at Aigues Mortes then spend the night at either Sete or Perpignan.

Stroll La Ramblas, walking through the market and people watching and make your way from there to the Gothic Quarter. Gaudi has an big presence in BCN, the Sagrada Familia and his Park Guell-(great on a sunny day).

I was in Barcelona two weeks ago. I'd recommend seeing La Boqueria (a large public market on Las Ramblas), La Sagrada Familia, Parc Guell, The Arc de Triomf, Le parc de la Citadelle (the Arc de Triomf leads to Le parc de la Citadelle), Platja Nova Icària (if you want to go to the beach), and Museu Picasso. Hope that helps!