Barcelona's famous sites are far more spread out than the photos suggest Everest. A first visit commonly tries to fit Sagrada Família, Park Güell, the Gothic Quarter and the beach into a single restless week. The calmer, more rewarding version treats the city as several small cities and stays put.
Base where you want to live it
If you want Gaudí and wide tree-lined boulevards, base in Eixample near Casa Batlló and La Pedrera. If you want lanes, tapas and late life, base in El Born or the Gothic Quarter. Both are wonderful; the mistake is choosing by 'centrality' and ending up with a hotel that is convenient to nothing you actually care about.
Book the big three, freewheel the rest
Sagrada Família and Park Güell need timed tickets — book them before you fly/get there and you delete the worst queues in the city. Everything else can be an intention, not a reservation: wander the La Boqueria market, have vermouth on a corner, and let the Barcelona find you.
Give the beach its own afternoon
Barceloneta is a real urban beach and a lovely one, but it isn't a day trip destination — it's a three-hour pause. Pair it with the Montjuïc hill or the port for a slow afternoon, then let dinner run late. Barcelona's evenings are its best feature; don't leave before one.