I started reading SF in the classic vein — Burroughs, Kline, Brackett — and I’ve always loved their visions of Mars and Venus, and the planetary romances of slightly later writers like Heinlein.  Unfortunately, the planets we actually got are barren and boring to anyone but a planetologist.  Hence I've worked mostly on Earth, doing alternate history, or set my SF in other solar systems.
Alternate History lets us access fictional worlds otherwise lost to us; a very ancient divergence-point gives us a Venus (The Sky People) and Mars (In the Halls of the Crimson Kings, the sequel) that offer a broader canvas for adventure — and for the mystery of how they got that way.  It was a bit of a struggle to find a home for the project; every writer I described it to loved it, but publishers seemed a bit more skeptical.  However it turns out, I’ve had a whale of a time writing it, and I think — hope — that it will connect with readers who’ve wanted that headlong glamour.

It also has the charm of happening to us, or to people roughly like us.  It’s surprising how late definite knowledge of our closest planetary neighbors came in; hints in the thirties, but no definite knowledge until the fifties.  From then, of course, things would get different, wild and wooly.