My process has been to move a group at a time from their place on the bookshelf to the floor. After that, I stare at them for a few days, then I eventually put them into boxes and finally dispose of them.
I have given some to friends and some to my weekly men's group. I have donated some to the 'Mud House' which is a coffee shop for soldiers in Iraq. I have donated some to charity. I have sent boxes to my brother, some to a sister-in-law.
There is more to go but we are getting there. The bookshelves are spoken for so they will have a new home too.