I got a bit frustrated with parts of Shift because it gave me dates and I had no idea how they related to the events of Wool. But not in a bad way, just in a "I want to know more!" way. I enjoy books that have multiple threads.
I think you can move from like to love, but it's much rarer to move from dislike to like.
If you want something sort of postapocalyptic (but this is much more scifi-ish, more not-normal things happening) have you read the Gone series by Michael Grant? They get a bit silly but I enjoyed them. They are YA, but the kind that is still readable even if you are just an A and not so Y any more.
I love good sci-fi but don't think will get along with YA. Thank you for the recommendation, though.
If you are looking for post-apocalyptic, last of the six stories in Cloud Atlas is a very good post-apoc story. And the one before it is a very good dystopian story. Iirc, they would work well as standalone stories, as well.
An Orison of Sonmi 451 was my favourite of the Cloud Atalas stories.
Sloosha's Crossing (if that's right) was my least favourite (even though it was very Chrysalids, which I love) - I hate reading stuff that is written in dialect. I don't mind characters in different situations having different vocabulary, but when they are saying "real words" just write down the word.