I like Blank Generation a fair amount and couldn't really articulate why. I guess the guitar does elevate it - it would undoubtedly be worse with a straight-up punk sound. And yeah, I like those two covers (as well as the CCR one). Hell isn't a great songwriter or singer, sure, but I think he has a showman's instincts that work for this.
I knew Hell wasn't from New York though couldn't remember where. I actually read his novel Go Now as a teenager, which was not very good - the climax is SPOILER FOR A BOOK YOU'LL NEVER READ the main character having sex with his aunt.
The Posies' album Frosting On The Beater is pretty good, despite the terrible title. Amazing Disgrace is alright too. Both of those pack more punch than Dear 23 which is too maudlin for my liking. My favorite song of theirs is actually from the Reality Bites soundtrack.
Of note, Stringfellow has been accused of sexual misconduct causing Auer and the last remaining member of Big Star to split with him.
The Hollies are fine. They probably have 5 or 10 good to great songs, some of which I'm sure you know*, a lot of mediocrity, and some stuff that straight-up sucks, and their discography is annoying with no great albums so I don't know if it's immensely worth digging in.
*King Midas In Reverse
Long Cool Woman in a Black Dress, the one that sounds like CCR