FunkSoulBrother
I'd recommend Stranger in a Strange Land as it is considered the exemplary Heinlein, and also because of the book's significance onthe culture (Stranger ... is largely considered to be the book that 'launched' the 60's, for better or worse.)
Some of his works that have been made into movies recently, like The Puppet Masters are much better in print.
Keith Richard
Didn't even see your question until after Jazz had answerd; sorry.
Jazz
Not suprised that you're an Heinlein fan, not at all. Next time I'm in the area we should get together for a drink; you're one of a handful of people here for whom I'd really like to match a face and tone of voice on to the handle.
Phaedrus