The Rambla offers the family atmosphere of a small town with all the accessibility and benefits of a big city. Great walk with the family after a great meal and dessert from local providers and restaurants. There are supermarkets, pharmacies and plenty of restaurants/bars.
Plenty of variety and options. The beach is about a 6-10 minute walk, there are hotels, hostels and plenty of airbnb options around. Transportation is accessible, from public to private. Parking might be a difficulty in the street specially if you are not local to traffic rules.
As a family, this is a great place to chose for a short or long stay, 15 minutes from Barcelona and 6-10 minute walk from the beach.