Heinlein, Heinlein, and more Heinlein.
I've read a bunch of Heinlein before - Starship Troopers, Time Enough for Love, Stranger in a Strange Land, Farmer in the Sky, To Sail Beyond the Sunset, The Cat Who Walks Through Walls and so on, but my local used book store had someone drop off what appears to be someone's lifetime collection of science fiction a couple of weeks ago. I bought everything I didn't have already. And that included about dozen and a half Heinlein titles I had never read before.
So I'm reading those now. After that, I'll be going through the dozen or so Arthur C. Clarke books I picked up at the same time. Life is good.