Barcelona has an excellent public transportation system, including buses, metro, and trains. A single ticket costs €2.40, or you can buy a T-10 card for €10.20, which provides ten rides. Taxis are also a convenient option, but more expensive.
If you have more time, consider taking a day trip to nearby Montserrat Monastery or the Costa Brava coastline. For a unique dining experience, check out Tickets, a renowned restaurant with innovative tapas-style dishes. If you have less time, prioritize your must-see destinations and consider taking a bike or Segway tour for a quick overview of the city.