If you like action-oriented, old-time, hold-onto-your-seat Heinlienesque SF, I suggest you check out William Crow Johnson’s two books, Earth 2.0: Prison Planet and his new one, Earth 2.1: Regensis. Big books about bold characters that move. Three bucks apiece on the kindle. What’s not to like, eh?
Full Disclosure: Bill’s a writing buddy of mine (and he’s written me a very nice acknowledgement in 2.1!), so take whatever bias that might entail into account. But I’ve read them both and think they’re great fun.