Barcelona Transportation discount card

It wouldn't have been worth it for me. Barcelona has beautiful architecture, so I mostly walked. I only used local transportation a few times over the course of 12 days in the city (spread over two visits). A single Metro/bus/tram ticket is 2.40 euros, but you can buy a 10-ride T-Casual card for just 11.35 euros, which is considerably less than the 16.40-euro cost of a 2-day Hola Barcelona card. Neither the single ticket nor the T-Casual card covers the Metro from the airport, but if you're thinking of just buying a 2- or 3-day pass for a 4-day visit, you would only be able to use it for one of your airport trips. Since I was staying very close to Placa de Catalunya, I preferred to take the Aerobus (which is more expensive than the Metro); it terminates at Placa de Catalunya.

I haven't been out to Montserrat and don't know how much that transportation costs. If you're going to do that, I suppose it might tip the balance. Arriving at the beginning of what is predicted to be a rainy period might change things, too.