I would recommend books by Ben Bova
Ben Bova books I like include:
MARS
RETURN TO MARS
MOONRISE
MOONWAR
I would also recommend the Dragonriders of Pern series by Anne McCaffery. These include DRAGONFLIGHT, DRAGONQUEST, WHITE DRAGON and many more.
For fun and laughs I recommend the Myth Adventures series by Robert Asprin. These include ANOTHER FINE MYTH, MYTH CONCEPTIONS, MYTH DIRECTIONS, HIT OR MYTH and many more. These books are a very funny parody of fantasy books.
I also highly recommend
DAY OF THE TRIFFIDS by John Wyndham
CLONED LIVES by Pamela Sargent
CONTACT by Carl Sagan
WOLVES OF MEMORY by George Alec Effinger