By Season 11, the show was switching to a more digital-release format, but the DVD still packed a punch. This is the last season where the extras feel "full" before the later seasons moved to minimal features.
Several seasons include recordings of the cast at PaleyFest, which offer the most honest and unscripted Q&A sessions. If you are looking for a specific piece of information Supernatural Season 1 to 11 DVD Extras