Here's what I send out. I don't use an organizer, per se, because a) they cost so much to send out, b) no one fills them out properly, and c) I want to see the original documents (and scan them for my records!) anyway. Don't waste the clients' time transferring (and messing up) numbers, and I get it all and can compare with prior year lists for anything missing.
Anyone who keeps scanned originals, I highly recommend Gruntworx ( https://www.gruntworx.com/ ) to make an indexed pdf. That way when the CP2000 comes in a year and a half from filing, you can go instantly to the item the letter questions and see the original without slogging through a half-dozen or more pdf files littered with upside-down, back, and blank pages.
2021 Checklist - short organizer GF.pdf
Also - anyone who finds it useful can use my organizer - if you drop me a note I'll send the Word document and you can put your own firm info on it, and make any state-specific changes.