Here's something I've noticed, soundtrack-wise...
In the early years of the show, it was obvious they tried to make the street SOUND like an inner city street, Caroll Spinney even wrote one time that in those early years, a sound engineer played a record with traffic noises and such over a speaker in the studio, and it's evident as you watch, you can hear horns honking, engines revving, trucks backfiring, traffic cop whistles, even a short occasional siren.
That continued throughout much of the 70s, though I THINK by the late 70s, it was more subtle, with only like an occasional horn blow, but you could still hear some traffic noises throughout the 80s, but it
's like by the 90s, especially the ATC era, all that was phased out, and the only background sounds you could hear were birds chirping and kids playing... BUT, it seems like since Season 39, they did a bit of an about-face, and even though you still hit birds and kids, you can hear faint traffic noises again, along with other sounds like dogs barking and oddly enough elephants trumpanting (must be Horatio, lol).
Also, has anyone else taken this into consideration: the corner of SST where the lamppost stands was supposed to be like a four-way intersection (before Season 30 where that corner was blocked off by a dead-end alley, and the other corner by the Fix-It-Shop was blocked off by the subway station), yet the street sign never actually pointed in the direction of Sesame Street, but rather, in the direction of the intersecting street? I never really understood whyit was positioned that way, but I guess it doesn't really matter.