We (a retired couple with our 35 year old daughter and her friend) have a 4 hour wait in Barcelona Airport between flights (afternoon in late October).

Any advice on:-
- what we could do in Barcelona during that time (tourist destinations; sightseeing tours; interesting shopping; etc)?

- airport/city transport availability and timescales?

We hope that we can arrange something similar to when we had a 5 hour stopover in Minneapolis - we visited "Mall of America" instead of suffering the usual discomfort and boredom in airport surroundings.

Any informed comment will be welcome

Jim