I liked the extras on Season 5 and 6. Though some may disagree, they focus one aspect or special episode. Season 5 has one doc that focuses on the Trials and Tribulations episode exclusively. That was well done. And Season 6 focuses one doc on the marriage of Dax and Worf. And another that...
Somewhat back to topic, I recently found the Star Trek Deep Space Nine Companion by Terry J. Erdman. It's a great book I keep near me when I watch DS9 now that I've been collecting the DVD's. I meant to buy this book when DS9 wrapped production. It's a wonderful book I highly recommend. It's the...