I'm sad about the first appearances of Slimey and Linda both being lost.
And I think there are other notables in there, too. Like one of only two appearances of proto-Maria, the only two guest appearances made by Cleavon Little (one of which has Big Bird building a rocket which sounds really fun), and three Pete Seeger episodes (one which has a song about MLK).
There's also an episode where Molly (Charlotte Rae) sings "
Believe in Yourself" to a little girl that I was really hoping to see, and the lost episode where Jesse Jackson performs "
I Am - Somebody" (which we've all see on DVD) has two other orations by him that I'd like to see. I'd be bummed about the lost Mudman episode if we hadn't found some episodes with him recently, but there's a version of "Sing" we'll never get to see, and some other assorted musings.
So, not all 60 of them are
notable, but there's some significant stuff in there, IMO.