I also posted this in the top ten anything thread, but I've compiled a list of top ten episodes I'd recommend checking out if the main purpose to watch is for wiki research. There's things from the guides I wonder and there's things I've seen people mention that happen in certain scripts.
10. Early episodes with Irvine – some scripts call her Irving, was that name used in the actual episodes?
9. Season nine episodes (including episode 1184) with an unnamed dog who may or may not be Barkley
8. Suzanne Farrell – Scarecoe’s to do list on his user page mentions “At the Barre” naming Herry and Telly in one script, another naming Grover and Herry, and episode 1334 has a sketch that could be this (maybe both were the same but listed a little differently), with Suzanne Farrell getting Grover, Herry, and another monster to stretch on a barre – could that monster be Telly during his transitional period between his original television-obsessed personality and when Brian Meehl gave him the personality he’s known for (Telly likely wouldn’t have been identified by name in any scripts from that period)?
7. Can You Guess? – is Big Bob the puppet that would become Guy Smiley? What puppet was used for the contestant, Billy Monster (I doubt it’s the same Billy Monster from the later Here and There sketch with Grover and Herry) This segment first aired in episode 26, but also appears in episodes 57, 74, and 119.
6. Episode 21 (Balloons segment – which monster is used?)
5. Episode 372 (It includes “Before and After”, are the parts with Buddy replaced with a different character? )
4. Episode 441 (I’ve been told that the script notes that the first season sketch “everybody scratch” ends with Bernice on Bert’s back, when the segment is known to end with Beautiful Day Monster scratching Bert’s back; was the whole segment remade by then and the script doesn’t make it clear? Did the script make a mistake? Was there actually an alternate ending filmed?)
3. Episode 1259 – I’ve been told that Bruno has a lot of dialogue in the script but it’s pointed out that a lot of that could have changed by the time it aired, would be great to know if his first appearance was dialogue-heavy
2. early Elmo episodes – to determine Kevin Clash’s first performance as Elmo (and maybe to determine Richard Hunt’s, though I have a feeling that’s the first after Brian Meehl left)
1. Episodes where the trusted sources were unable to provide the wiki with a full rundown (including episode 2806, 2823, and 2974; the script sourced for episode 1389 is missing a page; The script sourced for 2600 was an edit for a pledge airing; I've heard that one season 11 script isn't the final aired version but can't remember which one)