(Reference links: stream all episodes; read all transcripts; the Weather playlist on YouTube (through ep. 31).)
These are so great. The structure of parallels and differences; the way Kevin sounds so friendly and normal at first that the references to Night Vale's recording booth being dry and bloodless are minimized (I completely missed it the first time through); the way that little clue about Kevin's reaction to the booth allows you to determine who's reliable and who's not--see the comments to the linked post about for what was really happening in Kevin's booth; the creepy worldbuilding about StrexCorp's domination; that "helpful pandemics" is on both Cecil and Kevin's list of things big (government/business) provide.
It took me a little while to get this, but I gather that (a) Night Vale and Desert Bluffs are generally doubled (except Steve Carlsburg, interesting) but not identical (the Mayors appear to be different genders) and (b) the Sandstorm brings in literal doubles, which you have to be outside to find. It's kind of confusing. Which is appropriate, I guess!
I also didn't realize until the credits of 19B that the weather is also doubled, same song, different performers, which is fucking brilliant. (Though the first version, right after Kevin, using the lyric of just "lie" over and over again may be a touch too obvious? I don't know. It's pretty, anyway.)
In "Yellow Helicopters," does Cecil remember StrexCorp from his trip to Desert Bluffs, or did he find out about StrexCorp some other way?
Finally, the proverb for 19B is apropos in a way that they don't usually bother with, but I suppose it is part of the credits for "Welcome to Desert Bluffs": "Step 1: Separate your lips. Step 2: Use facial muscles to pull back corners of mouth. Step 3: Widen your eyes. This is how to be happy."