We are flying into Barcelona for spring break this year with our 17 year old. We have 8 days total in country. Would love opinions on staying all 8 days in Barcelona and maybe taking 2 or 3 day trips? Or, split up the trip with 4-5 days in Barcelona and 3 days staying on Costa Brava? We were not planning to rent a car.
I would include the Costa Brava.
With 8 days in Barcelona, you can really do it justice; take in a show, see all of the Gaudi/Modernista sites, take a walking tour, tromp all over from Barceloneta to Montjuic to Tibidabo. You could do a day trip to Montserrat and another to Figueres. And you wouldn't waste any time switching hotels and hopping trains.
But, there's nothing wrong with going somewhere else for variety sake. Head's up... If you're primarily interested in swimming, you may find Costa Brava is a bit chilly that time of year.