I read everything Heinlein wrote, and ‘Tunnel’ is at the top of my list, followed (in no particular order) by ‘Puppet Masters’, ‘Sixth Column’, ‘Door into Summer’, ‘Starship Troopers’, ‘Double Star’, ‘Time for the Stars’, ‘Starman Jones’, ‘Farnham’s Freehold.... Ahh, what the heck - - ALL of them!
Freehold is chilling in today’s Islamic light.
I even bought my copy of "To sail Beyond the Sunset" in the Bookstore that was in the same area where Doc Pemberton's first glass of Coca-Cola was served at Jacob's Pharmacy, at the corner of Marietta and Peachtree Streets in May of 1886.