Lynness, sci-fi and scary

I haven't posted for a while for 2 reasons. 1) seminary started and 2)
I haven't found a satisfying sci-fi book. Not that I haven't been
reading. I read several stories some sci-fi, some not, from Orson Scott
Card's "Maps in a Mirror." I think the short story, like the one-panel
cartoon, takes real talent to pull off well. And he does. Most of what I
read was very memorable. Some disturbing, some brilliant, some both, but
very memorable. But, I wasn't satisfied. So checked the shelves for a
couple of the big names in sci-fi in the library. I ended up taking
Arthur C. Clarke's "The Songs of Distant Earth," which I found very
mediocre, though I did like his very believable but brief attention to
the social reaction of earth's peoples after they find out that the sun
will be going super-nova by a certain date (some have the "eat, drink,
and be merry, for tomorrow we die" attitude, some use all their talent
and wealth to try to find solutions for taking people off earth and
transporting them to other planets, some use it as proof that there is a
God - we've been wicked and he's done with the warnings- and others use
it as proof that there is none, etc.).
I am interested in the idea of alternate histories (which comes into
sci-fi when the idea of billions of other alternate universes where just
one little decision is different and is reachable by means of science)
and read a few alternate history short stories, but still was not
satisfied. So I kept looking. I've requested a few that I've heard of,
to see what they're like "The Positronic Man" (from Abby), "Ringworld,"
but haven't received them yet. I like sci-fi, generally. Not the
multitude of Star Trek sequels and spin-offs type, but I am not opposed
to suspending reality and imagining the future or anything (I do have a
friend who dislikes books or movies based on anything that is not REALLY
possible, so she doesn't like any sci-fi or fantasy, including HP,
etc... I however, have no such aversion). But I want something that is
satisfying. I don't know exactly what I mean by that, since I haven't
taken the time to figure it out, but I did find "The Host" satisfying
(but couldn't count it for this month, since I had already read it...)
If I find another that is satisfying (or if you find one for me!) Then
I'll post it.
As for October, I don't like to be scared, either...I'll see what I can
find. Maybe a Michael Crichton sort of thriller. That might be right for
me.