I've been trying like hell every since leaving college to turn myself back into a "reader". Its been nearly 4 years, and I'm not quite there yet, but getting closer. As stated, I did finish "Time Enough For Love" which is quite long (and quite Long, as well), which is an accomplishment, but it took me over a month, which is pretty pitiful. I can remember a time of reading voraciously, but its just been very difficult to get back into the habit after college beat it out of me.
Finishing TEFL reaffirmed my love for (what I call) "classic sci-fi", which includes most things from the golden period from the 30s thru the 60s. (HG Wells and Verne, would go under pre-classic or original in my classification system). But mostly I'm referring to Asimov, Heinlein, Herbert and Clarke (all of whom wrote some outside this period). The real sci-fi from these folks is far more about exploring a universe of ideas and using the possibilities of science to explore questions of philosophy and nature and humanity. It seems like so much of whats out and around now is just a Robert Louis Stevenson adventure book in a different setting.
I've been told by my friends who enjoy the same things I do about Scifi that there are some current authors writing good books in the spirit of the classics. But I've still got a lot of catching up to do, so I'm going to stick with the big four for a while yet until I get through a fair amount of them. I've never been a huge scifi reader, so I've only gotten a few of them under my belt.
But back to TEFL; a book that can challenge the prevailing opinions on marriage, democracy, longevity, and incest, all while being witty, informative, and using a non-traditional format automatically gains my respect. Heinlein is always challenging, which I love.

Current authors that I have read and consider of similar caliber to the classic sci-fi masters (Classic masters: Heinlein, Asimov, Clark, Niven, and to a lesser extent, Silverberg and Herbert).
Orson Scott Card: "Writer of the Terrible Choice"
He is a fiscal democrat and a social republican (he is a practicing Mormon) and hence, the antithesis of me. But I love his work anyway. His favorite themes are compassion and community. His best work: The original Ender's Quartet (Ender's Game, Speaker for the Dead, Xenocide, Children of the Mind) and any of his short fiction.
Kim Stanley Robinson: Created a believable Martian society from it's first colonists to about 200 m-years of development. HIGHLY advanced in its scientific and philosophical content. His favorite themes are (arguably) evolution and revolution. His best work: The Mars Trilogy (Red Mars, and especially Green Mars and Blue Mars).
Dan Simmons: Writes extremely strange, non-linear stories with a soft-core feel. He seems to be a great lover of classical poets and mythology as he features them prominently in his books. Once referenced in TMQ. His favorite themes are undecipherable to me (Seriously, someone else who's read his stuff... what are his themes?). His best work: the Hyperion Novels (Hyperion, The Fall of Hyperion, Endemion, The Rise of Endemion). "The Lord of Pain Awaits"
Stephen R. Donaldson: Another soft core writer. He reminds me of a modern day Dostoyevsky. If you wish to read about what keeps a human going despite unrelenting suffering, read his work. His favorite themes are perseverance and the futility of power. His best work: the Ring Cycle themed Gap Saga (The Real Story, Forbidden Knowledge, A Dark and Hungry God Arises, Chaos and Order, and This Day All Gods Die) Also fantasy: The 2 Thomas Covenent trilogies (Lord Foul's Bane, The Illearth War, The Power That Preserves, The Wounded Land, The One Tree, White Gold Wielder).
Andy made me read some Heinlein to "understand" him (ANDY) better. I thank him for it all the time. Heinlein gives women a sense of feminity, intelligence, motherhood, marriage and sexuality; proving to us that we can be all that we want to be, not what other people want us to be.