Well, I was going to say the songs "Everybody Sleeps" and "Dance Myself to Sleep" but I guess those are out of the running due to overplay.
But anyway, there's lots of great sketches with Ernie and Bert in their respective beds. Also, there's a good one with Grover in his bed talking about going under the covers and pretending that he's on the surface of the moon. And another one where his mom comes to give him a glass of water. Of course, I personally love the ones where Ernie wakes Bert up to tell him something (and Bert's almost always sound asleep and not wanting to be bothered) and then promptly Ernie winds up losing interest and falling asleep while Bert is left awake and frustrated. One particular time was when Bert and Ernie were camping and Ernie pointed out all the sounds of the woods. (At one point, he mentions a frog ribbitting and asking Bert, "Remind you of anyone we know?"
) -(I love that era. Back when Kermit was an active member of Sesame Street!) Anyway, there's actually a cool Sesame Street video that was released that features Maria telling Big Bird and Snuffy bedtime stories (most of them being nursery tales reported on by Kermit the Frog with Sesame Street news.) At the end of the video, Kermit himself pops up in his trenchcoat and says he's tired from all the reporting and tells Big Bird to move over and snuggles up with Big Bird and Snuffy in Big Bird's nest!!! That is so cool and cute!
And you have to mention Ernie's dream of balloons all over Sesame Street because he's scared of the dark. (Balloons are something he likes that Bert told him to think about to calm himself down.)
And there's Bert's dream of ice skating and that really peaceful music. And Ernie and Bert singing "But I Like You". And there's "Imagination", which is another great lullaby. And the ultimate lullaby would have to be "I Don't Want to Live on the Moon"!!!!
(And Big Bird does have a distinctive snore!)