Is it really worth the hassle and the stress? I vote no. Public transport is really good. I even take the bus.

we recently stay at the Hotel Maria Cristina...

"Hotel Maria Cristina is an integral destination for international explorers. Located in San Sebastian’s historic city center and overlooking the Urumea River, it is surrounded by gardens and promenades just a short walk from white sandy beaches"

It can be pricey but we were able to secure a fairly reasonalbe price by paying for the room when booked - about 2 months in advance.

The room had a fabulous view of the sea! And, as a treat, it has a wonderful spa as well!

Enjoy the city!

This is a useful PDF file about the surrounding area of San Sebastián.
http://www.gipuzkoa.net/gipuzkoaturismo/docs/100_en.pdf

We stayed at Maria Cristina and it was lovely - beautiful large room with sea view. Drove rental in Bilbao and it was no problem at all.

Try with apartment rentals for your accommodation

http://www.linksansebastian.com/index.php?chIdioma=EN