I’ve just finished reading John Scalzi’s Old Man’s War. I understand why the reviews have compared it to Heinlein, beyond the obvious nods, the book is like Heinlein for grownups.
Don’t get me wrong, Heinlein is one of my favorites. Once I discovered him, I devoured all of his books; some I loved, but some I was too old for. I miss the thrill of romping through space and Old Man’s War brings that back for me along with very real, very adult emotions and questions. Highly recommended.