A classic, yet good book: To Kill a Mocking Bird. A great book...I read it in school as an assignment and read it again because it just...touched my heart in a way.
My mom LOVES the Twilight series, and she is about 45! A co-worker told her about them and let her borrow them. I stopped reading at New Moon, but she had them all finished in about 2 weeks.
For out-of the-box scifi lovers, heres a book you might like: The Raw Shark Texts by Steven Hall. Similar to The Matrix, very mind bending.
For the animal lovers: Animals In Translation by Temple Grandin. A great book, gives you insight on autism and a new understanding of the way animals behave. Very re-readable!
A short, 153 page book that you could read in one afternoon on the beach: Grayson, by Lynne Cox. A woman goes for a morning swim and meets a baby whale...a sweet, hardy book.