IMHO, you should attend as many interviews as possible.  It is a good way to know a lot of companies.  You may not work for this company now.  But, you want to work for this company or this industry some time down the road.  Interview (especially those that you are not interested in getting a job from them) is a good way to do some research on some company.

Dreamer

Of course not.  I am refering to people that has no job now.  For people working, you have to think more carefully whether it is worthwhile for you to go...
Dreamer