The Renaissance Hotel is a great spot, near the airport. They offer shuttles to the city center, Las Ramblas, so you can ride the shuttle, go into town and see the sights! If you happen to have status with Marriott, this hotel has a 7 day a week club, with breakfast, evening snacks and all day drinks.
Barcelona is a beautiful city. There's a hop on hop off city tour available from the Las Ramblas area that could give you a great look at the city highlights.
Have fun!^