Oh lucky you! I’d love to have the whole Stephen King canon still ahead of me. And The Stand is one of my favourite books - I recommend it to dubious friends all the time and no one has ever not enjoyed it.
The Shining and Salem’s Lot are both true horror. I think The Shining is the better book in many ways but Salem’s Lot I read as a teenager and have a soft spot for. I’m also a big fan of Carrie and Firestarter from his earlier career. And his short stories are pretty terrifying - almost more so than his novels, I think.
If you get to the end of The Stand and still love it, then I’d try some of his other big reads - IT is the obvious one but I don’t think of it as horror. There are lots of scary bits but it’s about childhood and growing up more than scares. 11.22.63 for me is the book most like The Stand in terms of its scope and ambition, though not horror.
But really, with a couple of exceptions (for me, Rose Madder which I hated and found dull in equal measure after the very good first half and Revival which was just a bit meh) you can’t really go wrong. He’s written so much and though his endings are sometimes a bit wonky - almost as if he just gives up - I love reading him, because although there are so many different ways he tells stories, I really do think he writes better than almost anyone about those human emotions that don’t always get airtime in literature, and in particular about children.
That was a bit of an essay, sorry. But I do think there is a lot of snobbishness towards King but only from people who have never read him, so I'm always keen to spread the word.