Anonymous wrote:OP: What did you do/how did it go? I'm doing this too but with a 10 yr old.
Not OP, but--
You may enjoy taking the cable cars to/from Montjuic Castle. Great views and a fun experience. Funicular railway to Montjuic is also interesting.
La Central bookstore has two stores in the city, one in an old monastery (Raval) with a coffee shop and interior patio garden. Wonderful collection of children's books.
Parc Güell is a must, but, of course it has become very crowded (the entire city). Book Sagrada Familia tix asap bc they sell out. My fav Gaudí is the 1920s apartment La Pedrera - Casa Milà. I get quite dizzy from the Gaudí architecture because of the unexpected shapes, drink plenty of water and dress for comfort! Don't be afraid to taxi/metro around the city, it's quite hilly and nobody wants heat exhaustion.
The water is yuck, but Barceloneta beach is easy to get to and a nice stroll.
You will see a lot of anti tourist slogans all over the city because tourist apartments/tourism are viewed as the reason that housing has become unaffordable for residents. Don't be surprised if people are very rude to you if you speak Spanish, even in tourist areas. Learn how to say hello and good bye and thank you in Catalan and they will be wowed. Or speak English.