These are my settings:

Spoiler

Aspect Ratio: 16:9 Widescreen
Resolution: 1600x900
Antialiasing: 4 Samples
Anisotropic Filtering: 4 Samples

Texture Quality: High
Radial Blur Quality: Medium
Shadow Detail: High
Decal Quantity: High

Water
Reflect Land, Reflect Objects, Reflect Trees.

Basicly I play on high settings except I took down the antialasing down by 4 from 8, also with anisotropic filtering.
And in the open world I have from 38 to 60 frame rates, while inside caves or other places I have 50 to 60 frame rates depending if there is alot of action.
And the only mod\plugin I am using is the Offical Skyrim HD textures.

So what kind of settings do you play with and how is the performance (frame rates)?
And what kind of mods do you play with that could have an impact on the performance such as better graphic mods, etc.