You should know this already. However, my suggestions:
1. A good UV or 81B or both. (if you're going high altitudes, there'll be a blue cast from the UV light). Warming is always good for landscape, esp as you're going near winter.
2. ND8 or higher. In my view, ND4 is neither here nor there, not slow enough for waterfalls, but slow enough to prevent handholding.
3. A warming polarizer if you can afford one. Normal polarizer has a tendency to make things a little cool.
4. Fill flash for people shots under bright sunlight.
5. Good lens hood.
6. Incident light meter/spot meter for landscapes.
7. Grad ND 0.6 or 0.9 for landscape.