Spain/Portugal/Gibraltar - One day in Barcelona, suggestions?

We'll be in Southern France for a week, and work in a day long trip to Barcelona (arriving the evening before, leaving in the early evening and driving back towards Arles).

My partner really wants to see Sagrada Familia, and I imagine that will take a goodly part of the morning. That leaves an afternoon. What would you see/do?

I loved the Parc Guell and the Fondacio Miro - both would easily fit into an afternoon.

However, I'd also leave time to eat, and to eat well. There's some fantastic food to be had in the city, and it would be a shame to have to rush it, or to eat at the 'wrong' time (i.e. too early).

I would also recommend Parc Guell (and the Miro Foundation), but another option would be the Picasso Museum and the nearby Barri Gotic/Cathedral area (La Rambla is also here but I never saw the appeal of it).

Aside from La Sagrada Familia and Parc Guell, you can do a a walking tour of Gaudi's architectural works.

Not to hijack this thread, but maybe it will help the OP as well. For a night, what restaurants would you recommend for incredible food for say no more than 50 euros a person? Food and drinks, if possible. Will be at the Le Meridien, but doesn't have to be in that area, but if it is, a plus!