Honestly, I tend to go into a reading coma, where I do very little other than read for like a day and a half, two days. I can finish a good book in that time (unless it was written by Robert Jordan), and I usually get to the end before anyone can ruin it for me.
I also avoid the internet when I'm reading, so I don't have anyone who flipped open to the end and just blurts out the ending to worry about.
-kv