Flowers for Algernon (Daniel Keyes)
The Effect of Gamma Rays on Man-in-the-Moon Marigolds (Paul Zindel)
The Things They Carried (Tim O' Brien)
This Side of Paradise (F. Scott Fitzgerald)
Something Wicked This Way Comes (Ray Bradbury) Essentially a children's sci-fi novel, but it doesn't read that way.
A Moveable Feast (Ernest Hemingway) My personal favorite (along with his short stories, which I highly recommend), but if it's your first time reading Hemingway, might be better to go with The Sun Also Rises.
Revolutionary Road (Richard Yates)
On the Road (Jack Kerouac) *One of my personal favorites, but most people either love or hate it, so maybe save this towards the end.
On my own reading list:
Speedboat (Renata Adler)
Money (Martin Amis)
Love in the Time of Cholera (Gabriel Garcia Marquez)