Thanks to all the commenters here and at The Valve for the suggestions and information about SF novels; I certainly have a reading list now. (And please keep the suggestions coming if you still have them!)
I think I'm going to get started with Solaris—I already have some familiarity with it through Tarkovsky's adaptation (but not, thankfully, Soderbergh's), and Rich's comments about it on The Valve make it seem like an important starting place: he says, "It’s just that if you’re going to try hard SF, I think you’re better off with Solaris first; if you don’t like it, you’re not going to like anything in the subgenre," and, "I was particularly struck by Solaris because I have a science background, and it’s one of the few SF books I’ve read that struck me as really having anything to do with actual science." That sounds very interesting to me. Octavia Butler's coming after that. And Adam Roberts's Land of the Headless is likely in flight somewhere from Amazon to me. Others will follow, no doubt.
I'll (of course) keep you all updated on my progress. Thanks again!