be forewarned
There Are Doors is more subdued modern fantasy than science fiction. Maybe something like de Lint, though far less Gothic. It's also a bit of a romance, though "romance" here means the aching, impossible love between an autistic department store salesman and an immortal woman from another world, and not the Harlequin bodice-ripping kind. It's a haunting, beautiful story, but it's pretty spaceship free. Think of it as a Celtic legend circa 1200 AD rewritten for 1985 and you sort of have the picture.
If you want a one-shot of Wolfe, you could do worse than to track down Seven American Nights in some collection. A good novella that will give you an idea if you like his style or not. Most of his better novel-length work is in 2-4 book cycles, which makes it hard to recommend off-the-cuff. I think his Wizard Knight series is vastly underrated, and that's only two books, so, uh, start there!
Ender's Game is okay. There's no shame in reading and enjoying it. It's just kind of forgettable fluff that has been elevated to canonical status--like the Da Vinci Code of SF. At the very least, skip the fucking sequels.
Can we count Lethem's Amnesia Moon as post-apocalyptic? It's kind of during-apocalyptic. Anyways, it rules.
If you want a dark post-apocalyptic comedy, read Dick's The Penultimate Truth.
Canticle for Lebowitz is awesome/must read.
The Road was okay, if far from the most beautiful book I've ever read.
I like Atwood but found Oryx and Crake to be mediocre, sadly. Read The Blind Assasin, it has a few secret SF chapters.