Maybe they could have them themed around classic characters who were primarily in street stories, like Big Bird (it'd be great to see footage from the season 7 episode where Big Bird runs for president, or footage from the "Number 4 Show" besides "I Just Adore Four"), Oscar, and Mr. Snuffleupagus.
Maybe there could be a video about how Snuffy was believed to be imaginary. Select episodes where they think he's Big Bird's imaginary friend, ending with the season 16 premiere where some of them decide to believe Big Bird and then the season 17 premiere.
Or maybe a compilation of all the snow episodes from season 5 (I've got to believe that there are more "snow day" episodes than just the ones on iTunes and Netflix). Maybe even some snow episodes from later seasons.
In recent years, there have been single-disc releases with pre-season 33 street stories (mainly from seasons 30-32), so I guess it wouldn't hurt to release more of those.