From Barcelona to Pamplona

The buses in Spain are WONDERFUL. They are clean and comfortable and nothing like buses in the USA, and are less expensive than the train. They also go everywhere... so if you cannot find a train to Pamplona, don't be afraid to try the bus.

I agree, the buses are very good. I won't take internal flights in Spain/Portugal again. You waste too much time with check in, security and delayed flights. And baggage on the discount airlines is a minefield in itself. The bus and train stations are easily accessible by metro, and are usually central. Whereas the airports are usually outside the city. However, saying that, transport to Barcelona airport is very good. They also have a premium bus service on some routes where you get a hostess, movie, food and drink, for maybe 10 euro extra. Highly recommend it for the longer trips. And you get to see the beautiful countryside speeding along the freeway.