I was 11 years old and already a huge Trek fan as was my dad.
We watched the preview show, and caught all the episodes as they aired and kept watching them as reruns through the years. I was also reading all the new Bantam and Ballantine Trek novels I could find.
I loved how Alan Dean Foster fleshed out the stories. Sadly I could never get my dad into any reading whatsoever.
I've got the TAS boxed DVD set and still rewatch them all once or twice a year. Great series.