If you decide to get the D800, I would recommend replacing the 11-16mm and the 17-55mm with the 14-24mm or the 16-35mm and the 24-70mm or the 24-120mm.
If the additional funds for the lenses are not in the budget, I would go with alternate #3. Add the 300mm f/4 and a TC and a good tripod and head. I would also make sure to bring at least two large capacity portable hard drives to back up your image files. Good Luck and Enjoy your Nikons!