Public transport is easy in Barcelona. You can buy books of tickets at the airport and just use them on the underground, which serves everywhere.
I think its a good choice for three days. Rome might also have cheap flights (as they're plentiful) and that's got lots to see and do with decent enough weather in October.
I think its a good choice for three days. Rome might also have cheap flights (as they're plentiful) and that's got lots to see and do with decent enough weather in October.