Since you already have a 200mm in your arsenal, and are considering a longer lens, such as a 300mm, you might want to take a look at this Nikon Simulator to see if, indeed, that extra 100mm will accomplish what you desire. 300mm isn't really all that long under certain conditions. Cropping may be your best solution, and thus a higher MP count on a newer body may be the answer. You can compare the reach of your 200, to that of a 300, to see the effect. Good luck.