Thumbs up on Ringworld and the Engineers. Do not go further in the series. He wrote more, years later, after his poor mind had gone. Do not attempt.
Thumbs up on Good Omens, and really, anything else by Gaiman. I like Prachet and all, but Gaiman's work is more my style. Here though their styles blend perfectly.
Quicksilver I haven't read. I adore alternate history, but my friend who have read it don't recommend it.
Starship Titanic is alright. Shouldn't be on top of the pile though.
1984 deserves a re-read, yes - particularly in light of today's politics.
I haven't read the Stokers, though I've seen the movie version of Lair of the White Worm. Which is gloriously bad, in a very fun way.