Below you can see the front view size comparison of Nikon D300S and Nikon D300.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Nikon D300 is 13g lighter than the Nikon D300S but we don't think this will make a significant difference.
Also keep in mind that body weight is not the only deciding factor when comparing two interchangeable camera bodies, you have to also take into account the lenses that you will be using with these bodies. Since both Nikon D300S and Nikon D300 have the same APS-C sized sensor, their lenses for a similar focal length and aperture will be similar in size and weight.