Another book down on the Heinlein reading project, and (whoa) 32 to go. Podkayne of Mars came out in 1963, after Starship Troopers and Stranger in a Strange Land, and it's another indication of how easily Heinlein could shift tone and topic even within the SF genre.
The first-person (usual) narrator, Podkayne, is neither a tough-as-nails space marine, nor an orphaned Terran raised by Martians. Poddy is an eight-year-old human girl, born and raised by humans on Mars.
Sorry, that's eight Martian years. As she takes pains to point out, you multiply by 1.8808 to get Earth years. By dubious political/legal maneuverings, she and her younger genius/sociopath brother Clark wangle a grand tour of the inhabited planets aboard the luxury spaceliner Tricorn, escorted by Great-uncle Tom.
Well, they get as far as Venus.
I found it pretty enjoyable, and if you're gonna gripe about Mr. Heinlein writing in the voice of a very precocious teenage girl… well, how would you know about how such a girl, raised on a future Mars, might think, act, and say? Hmph.
It's all fun and games until… whoa… about three-quarters of the way through the book, where the dangerous hints previously sprinkled throughout come to a head. The true point of Uncle Tom's journey to Earth is revealed, as are the murderous lengths to which his political opponents will go to thwart him.
Consumer note: I got the "original" version of the book in paperback (retail $0.95, but I got used, marked down to $0.50). Since then, Heinlein's original ending to the book has come to light and it's very different. He was pressured to change the ending at the very last minute; just one page, but a 180° shift in tone. I understand current editions have both endings in place. The book's Wikipedia page has the details, but avoid that if you're spoiler-adverse.