My resolution is high because ped LOD is tied to the resolution. If you don't turn this up then peds in the distance are grey.  The lower the resolution, the lower distance the LOD shows. Also, a higher resolution helps with getting rid of some of the aliasing.

Texture Quality: High
Reflection Resolution: High
Water Quality: High
Shadow Quality: Medium
Night Shadows: On (Keep off if you wanna get over 30 fps in the night.) (May cause some stuttering at night as well)
Texture Filter: Anisotropic x4

These settings you can turn down if you wanna get to over 30 FPS
View Distance: 70
Detail Distance: 70
Vehicle Density: 50

Definition: On
VSync: On

I get about 2 to 3 hours of playtime