I didn't know he wrote books other than Science fiction. But why not?? He was prolific.. Why not be versitile, too?
Be Well.
The Door Into Summer is cool as hell. As is Starship Troopers. Heinlein is great about describing his views in the books and making his science and politics easy to understand.
I must admit, though, that Stranger in a Strange Land and everything after it just doesn't have the same feel.