One nice thing about reading (and reviewing) for pleasure, rather than for a class, is that I can pick and choose what I want. And in extreme cases, I can stop reading a book midway through, though that remains fairly rare for me. There's no question that there is no objective best set of 100 or even 1000 books, but I am reasonably satisfied with the core books that are on my shelves, or rather the bookcases upstairs. While I haven't really kept this updated, these posts give a good indication of what has made the cut for my personal canon: A-D, E-J, K-O, and P-Z. By the time I get through my current reading list, I'll probably have read 50% of these books (currently I am just a bit under 40%) and some are clearly ones I'll want to reread.
Most of these books or rather the authors come from one canonical list or another, and then when I agreed that the author had merit (or really I found his or her writing congenial to my tastes) then I often expand to get the core novels (or plays) by these writers. I particularly do like stumbling across books or authors that have been rescued from obscurity. NYRB does a good job, bringing slightly obscure books back to its readers, and Virago Press is focused on bringing more attention to female authors.
I'm currently on my fourth book by Elizabeth Bowen (The Death of the Heart) and I have to admit, there is just something that often rubs me the wrong way about her main characters, even though the writing is generally quite good (though she does seem to over-explain interior moods, which was something that I didn't like with George Eliot). Now with Elizabeth Taylor, I think I am a bit more in tune with her writing, and I particularly liked The View of the Harbor, though I was a bit bored by A Game of Hide and Seek, since I thought the main characters to be drips. (With both Bowen and Taylor, often the secondary characters are what makes their books rewarding, at least in my view.)
Anyway, while I was checking something related to Bowen's The Death of the Heart, I stumbled across Jonathan Yardley's Second Readings, which collects a number of columns from the Washington Post where he isn't just reviewing flavor of the day books, but goes back to some neglected books. I only looked at a couple of essays, but I thought that he was right on the money with Faulkner's The Reivers and Powers' Morte D'Urban. I even agreed with him on John O'Hara's Appointment in Samarra, though his review in the Washington Post was extremely laden with plot spoilers, so do be aware. This blog post lists all the books that he reconsidered during the project (just shy of 100 books), though the links to the original on-line reviews took forever to load. I think this is a case where checking Second Readings out of the library is probably the way to go.
Neglected Books is a blog all about relatively obscure books, and while I don't expect I will spend a lot of time there, I may occasionally pick up a title or two to add to my list. I generally prefer books that have come back into print over ones that sank without a trace.
I've circled back around to list which of the books I keep upstairs are particularly obscure and/or out of fashion. I'm not sure I should count any poets, since by definition they are no longer really part of the literary mainstream, but Aaron Kramer is particularly obscure, and yet I have 4 of his collections.
I have Waiting for Winter, which is a collection of short stories by John O'Hara, two slim story collections by Goffredo Parise (Abecedary and Solitudes), The Coast of Chicago by Stuart Dybek, Petersburg by Andrei Bely, Durrell's The Black Book, and several books by the South African writer Ivan Vladislavic (maybe not as obscure after these were reprinted, so they may no longer qualify). Totally obscure (and not reprinted) but downstairs (and thus not really eligible), I have two books by Maritta Wolff: The Big Nickelodeon and Buttonwood. So I guess those are my baby steps away from the received canon, as it were; while I like to think I have a fairly sweeping set of literary interests, I certainly don't spend an inordinate amount of time on OOP books.
Sadly, I don't have anything profound to say on this topic, but I would encourage people to read The Coast of Chicago and Vladislavic's The Restless Supermarket.