Funny this should be brought up. I've been in my most consistently read-y stretch of my life for the last couple of years, and I'm really glad. I'm a naturally slow reader, especially when I haven't read in a while, so I've tended to resist. But I seem to have broken out of that and I know I'm better for it.
What happens to you after you finishe a book, good or bad?
Depends widely on the type of book. If it's a novel and I enjoyed it I might make a note of it and look for other work by the author. If I REALLY enjoyed it I'll likely immediately grab something else by the author (the day I finished reading everything Douglas Adams had written was a sad day). If I didn't like it I'll find someone to complain about it to (ideally someone who liked it

).
If it's non-fiction I usually look for something else on the same or similar subject, or tangent off to a related (even if marginally) subject.
Do you put it away and not think about it or does it apply to your life in some way?
Depends on the book and the subject. I'd say that the only subject that I read that I consistently continue to ponder after putting the book down is anything regarding philosophy of the mind/consciousness. Agree or disagree with what I read, it's always on my mind.
Why do you choose to read certain books
Recommendation. Previous experience with the author. Referenced in a bibliography of something I liked. Nearby on the library shelf. Stuck in an airport. The title jived with something I was thinking. Any combination of the above, and more. It's kind of a stream of consciousness decision usually.
For example, I grabbed 2 books at the library today. I was pulling titles from the bibliography of a Douglas Hofstadter book. The first one I grabbed was
Waiting for Godot, which I've never read (straight out of the pages of
Duh Magazine, but damn if that isn't a good play!).
The second title I was looking for on the shelves was a book called
This Book Needs No Title, about paradoxical word play (e.g., "This is not a sentence.") and such. Despite being in the system, it wasn't on the shelf, probably mis-shelved or yet-to-be-shelved after a return. But as I was scanning the area around where it should have been, I spotted Paula Poundstone's book,
There's Nothing in this Book I Meant to Say. The conceptual similarity in title, and the fact that I've been hearing a lot of Paula Poundstone since I've been listening to Wait Wait Don't Tell Me on NPR regularly were enough for me to accept that as a fair substitute. Of course, the very next day our TiVo recorded an episode of Home Movies for the first time in months and it happened to be one of the 6 where Paula Poundstone voiced one of the main characters. Go figure.
and why do some read easy and other take forever to read?
I figure it's a matter of how closely the author's thought process aligns with your own.
Is there a satifaction or is it just to pass the time?
Definitely satisfaction. I actually hate reading as a time-passer. If I'm not interested in the book I can't concentrate and it's an absolute chore,
Have you ever finished a book or gotten halfway thru and nothing sunk in to where you had to start over again?
Never a whole book. I'll find myself re-reading a sentence, or a page, or a chapter due to my mind wandering, but as a whole I pay attention to the book.
That said, my long term retention is fairly horrible. With rare exception, by the time I'm reading the next book, the details of the previous one are pretty sketchy.
So why?
To keep it short, because of the opportunity to expand my thinking. I'm not one who gets lost in fantasy worlds while I read, but that doesn't mean it doesn't make me think in new directions.