I'm planning a trip to Bilbao, then take a train (Eusko Tren) to San Sebastian, then another train (RENFE overnight) to Barcelona. My husband wants to go to Paris from Barcelona and considering the time we have, I think the best option is to fly there. I've checked out Easyjet.com and it seems pretty good. We have maybe a week and a half or two weeks. What do you think?

Are you aware of the easy bus connections between Bilbao and San Sebastian?
www.pesa.net

The train from Bilbao to San Sebastian-Donostia is a bit slow, as already pointed out. The bus is a very good option and you can always take a taxi and be there in under one hour.

Thank you for the website. Seems like a better option to take a bus. Any idea on the cost of a taxi?

Note that the bus is an express bus that doesn't make any stops between Bilbao and San Sebastian. I doubt you would get there any quicker by taxi.

A taxi will cost between 130 and 140 Euros and it takes about 1 hour. The bus it's about 8 Euros and takes 1,10h. There are buses running every hour and early in the morning and late at night every 30 minutes.

Have you checked www.vueling.com for air connections between Barcelona and Paris?