I usually render at standard wide screen wallpaper resolution of 1680x1050 at 100DPI.  The render is going to be a showcase render for a model submarine I just finished.   Not a lot to it.  One infinite Plain for the ocean, one terrain for an island using built in C6 textures, the sub, the model, hair, outfit and shows.  Only one light source, a sun light, and realistic sky.  It just took over an hour just to do a spot render of the head and hair.