Legacy is actually a prequel to Eon - not quite a standalone as it helps if you've read Eon first but you don't need to read Eternity before Legacy.
Earth Abides George R Stuart. Pretty much the whole book.
These great standalone novels haven't been mentioned yet:
The Barbed Coil by J.V. Jones
The Wizard Knight by Gene Wolfe (published
Great on the reviewing! and Oh My on the marriage problems. I do hope things work out!
That's going to be hard to catch.