Almost seems like a companion novel to Earth Abides - happening on parallel Earths, that is. Same feel to the writing, same male/white narrator slant, but hey, the author is a product of his time. If you can get past that (and it's pretty minor in this), is a great read.
Would be excellent for book discussion groups as well.
"After the Night of the Comets, it's the Day of the Triffids" -- sounds like a great film teaser, doesn't it? = )