We plan to take the bus (PESA NET) bus from Bilbao ot SSebast. - I was looking on their website for where to buy the tickets / get the bus - it did not jump out at me. Can you please tell me where we will purchase the tickets and catch the bus! Thanks!

The location is called San Mamés, and here it is on a map:
http://maps.google.com/maps?q=43.261...num=1&t=h&z=18

See the buses huddled around the building? There are confusing array of bus ticket windows belonging to different bus companies under the roof.

you didn't ask this, but I once took that bus and hated it. Were I ever to go that route again, I'd rent a car to do it.

vespa - why did you hate it?

The seats recline and the person in front of me reclined theirs all the way until they were prone and their head was in my lap. Bus deposited me fairly far from where I wanted to go. I didn't like being tied to a bus schedule.

Roads around there are very easy to drive. It is a pain to park in San Sebastian, however, so for a future trip I would visit Bilbao before or after staying in San Sebastian, not in the middle of a San Sebastian stay.