Barcelona - places to see and restaurant recommendations

[Zippee]

I'm off to Barcelona with my wife in a couple of weeks for 4 nights. Neither of us have been before and we're staying at the Olivia Balmes, just off Las Ramblas.
As such, other than the big touristy stuff what should we be making a must see/do? Also any good restaurant recommendations around that sort of area?

[Zippee]

Thanks all for your suggestions I'll look into them.