Mentioning cassette automation, the most unique I saw was two cassette carousels, each holding 24 cassettes. The homebrew format was recorded with the typical tones and several single deck cassettes were used for 'currents', commercials and liners. All cassettes were Maxell UDXL II tapes but I don't recall if they were C-60s or C-90s. It was pretty much a lite rocker and it sounded pretty good.
I saw an FM automated with CD decks. It seems it was a typical automation system modified for a huge number of CD decks (all were 6 CD decks) that had the entire music library ready to roll. Commercials were on CD as well and station IDs on cart in what I think was a 48 slot 'insta-cart' (two rows of 24 cart slots). I want to say this was at the FM in Dickson, TN.
I have seen stations that operated on cassette for DJ assist. The worst was a small town station that had cassettes with 24-26 minutes of songs. The format was simple play one side of a cassette, then play spots and do weather, PSAs and such. Thus, the average hour was 25 minutes of music, 5 minutes of spots and such with the next cassette started at :30 to roll until :55 when more spots and such filled the next 5 minutes. Needless to say the station didn't do much and eventually shut down. It didn't sound good as the control room was a Radio Shack microphone, three or four dual deck Radio Shack cassette decks and a pair of Radio Shack mixers. Processing was a store bought unit. The station operated from a farmer's field in a little old mobile home. This was the 1980s and I doubt they ever billed more than $5,000 a month sold for whatever rate a client was willing to pay...50 cents to a dollar mostly.