I'm probably too late for elricho, but I just stayed at Hotel Rey Don Jaime I, Carrer Jaume I, 11 ( Barrio Gótico, 08002 Barcelona). Metro: Jaume I. Note the spelling. It's between two major streets (La Rambla and Leitana), and a very short walk to the Port Vell. Or, you can walk north to Placa de Catalunya.
The stadium is far from everything else in the city, so I would recommend staying downtown and just taking the metro once to see the game/museum. I think the Guell Pavillion is near the stadium (metro: Maria Christina) but that's about it.
About the hotel: my hotel was 70 euros for two people per night (1 room). The room is small, there were no bed bugs, and the only noise was from the hardwood floor, creaky iron door (I stayed at the Annex Hotel, which is across the street but owned by the same people), water running through the pipes; standard stuff you would expect from an old building in the Gothic quarter. So if you're a light sleeper, it's not for you. I had no trouble sleeping each night, so it was a fantastic location and affordable price. Every night, I could take a stroll down Leitana, then along Passeig de Colon, then up La Rambla. I only went to the stadium twice during my trip, once for the match and once for the Museum/Botiga.