Hello,
We did a tour of Montserrat, skip the line of Park Guell and City of Barcelona with Barcelona Day Tours and it was amazing. We were picked up on time and dropped of at our hotel at the end of the tour. Our driver and Guide were very knowledgeable and made the experience so much better. They get a 10 for communication during booking, cleanliness of vehicle and overall experience. If your not staying in Barcelona they have tours that will take you back to the ship or airport.