This is a very personal question... and one that is really dependent on your style of shooting. One thing you can do that I haven't seen mentioned yet, is to go through the EXIF data on your images, and see what are your more common preferred focal lengths for shooting.
For me, it's very strange. When shooting, DX, one of my most heavily used lenses was the 17-55. Since switching to FX a few years back, I thought the 24-120/4 would be perfect. I ended up selling it because I was always switching out for a different lens. I have a newer 24-85, but it just sits collecting dust. I just haven't needed it, and can't really say why.
I have lenses for most every situation, I just don't carry them with me everywhere I go.