No idea what your reading level is, but here are some of the suggestions I've made to customers recently:
Harry Potter, if for no other reason than the cultural impact
Ender's Game: children being taught to be elite military officers
Small Gods: satirizes religion, religious institutions, etc. If you ever want to read Discworld, this is a very good starting point
We Free Men: also Discworld, but YA-focused and about a girl who becomes a witch
Lamb, the Gospel According to Biff, Christ's Childhood Pal: author imagines what Jesus and his BFF Biff were doing for those thirty years missing not recorded in the Bible.
Kindred: a woman starts to travel back in time to the pre-Civil War South. She can't control it and she doesn't know why. Probably Butler's most accessible novel.
A Canticle for Leibowitz: humanity nuked itself back to the early medieval period and this one holy order watches it rebuild. It's hard to describe this book in a satisfactory way without just summarizing it, but it's one of my favorites and I've read it multiple times
The Giver: YA dystopian novel about a very structured society and the kid who is able to see through it. The sequels aren't too bad either
The Hobbit: much easier to read than Lord of the Rings, but full of the same heroics plus dragons, dwarves and a clever hero