And I just put a quick release plate on mine before reading this. It is an excellent lens, isn't it?

My Cokin graduated ND filters do produce a very slight warm tint. I use them strictly for reducing sky exposure when necessary, and do not find this detrimental. Same for any image degradation, which I have not noticed.
I don't believe I've ever used one when I had much detail in the lower part of the scene, so will run some tests on the clear section and check for colour cast and image degradation there. If I see any degradation here, I will go with Lee.
I have pretty much the whole P system, but have only used the graduated NDs, so cannot vouch for the others. Their polarizer is glass. I've never used mine.
I'm glad you made this comment, JimGuy, otherwise I would not have thought of testing these filters on fine details.

The best independent lens I can recommend from personal experience is the 400/5.6 Tokina AT-X 400 AF SD APO, mighty close to a Nikkor ED optically. Sigma and Tamron may also have offered something similar. At any rate, I believe you will have to shop used.
From my experience, Adorama and B&H are very reputable.
Go for the best condition you can. I will not say which one, but I bought a manual lens from one of them several years ago that, while the glass was like new, the zoom ring was excessively loose. I called, was told to give them a repair price from Nikon, I did so, and a few days later a check arrived in the mail. I don't know if they took my word for it, or checked with Nikon, but I considered that exceptional service.
Hope this helps. Good luck.

When I'm in the mountains or desert, my Cokin graduated filters are always close at hand. Happy shooting.

If you do not mind being limited to JPEG, the Nikon P520 with its full-frame equivalent of 24~1,000mm ED VR lens is fantastic. Any top quality fast zoom lens will be heavy.

I much appreciate all who have commented and educated me on bokeh. When out-of-focus is desired, or cannot be avoided, the importance of a lens with good bokeh cannot be overstated. People like you make this site what it is. Hopefully, my ignorance has benefitted others.
Thinking back, I do recall one gentleman who left with a fuzzy ear. But he had it when he came in.

I've seen no bad advice here so far. I personally prefer Heliopan filters and stepping rings for their brass mounts, their glass is at least the equal of any. Enjoy your trip.

Thank you for confirming my perception of bokeh. An environmental portrait, of course, is an entirely different matter, and most do demand good bokeh.
(I'm sure that if I had hung out a photo studio shingle 50 years ago, I'd be writing this on a pauper's home computer).

You make some excellent points, perhaps you can help me out here. What looks best to me where there is out-of-focus detail in the background, and what I consider good bokeh, is an easy, almost imperceptible transition from in-focus to out-of-focus, the smoother the better. I noticed this probably before I was in my teens, decades before I heard it defined. In the case of my preferred portrait set-up - an indistinct backdrop 5 feet or so behind the person - the image goes abruptly from in-focus to mush. My perception is that the bokeh characteristics of the lens is immaterial. But I've been wrong more than I care to admit.
I've probably done less than 500 portraits in my life, including 3 weddings and a couple of dance routines, a small fraction of my total work, so pretend to no expertise in this field - I offer my view as one I had not heard expressed before, that has been satisfying to me.
I welcome any and all comments and criticism.

You pretty well said it all, SS. I should have added that I do very little portraiture, and only for family and friends. No doubt some were disgusted with the results but, if so, they pitied me enough not to tell me so (I have a great family and great friends).
Mostly I've photographed to please myself, though while working for the Department Of Defense I did some product shots and documented some of my research projects, and my penchant for sharp focus has always held me in good stead. (I guess- at least the government hasn't rescinded my indefinite camera pass).
Each style is as individual as the personit, and if one is satisfied with his/her style, it cannot be wrong.
Thank you for your kind input, as well as the other responders. All make very valid points.
P.S. I have a few years on you, SS. Got hooked when a neighbor went away to college and gave me his "Roy Rogers" box camera. Took 620 film. The very first picture I took was of a brand new 1954 Ford driving by the house, when I was 11 1/2. Didn't have a clue what I was doing, but I panned it, the car was sharp against the blurred background. Come to think of it, I wonder just how much I've actually learned since then. I just may expand my horizon!

The comments to donmabry's question on The Best Portrait Lens (April 26, 1831:41) illustrate one great thing about photography - how personal it is.
Several commenters recommended certain lenses because of their good bokeh. If I see any kind of bokeh in my portraits, I have failed as a craftsman. I consider every part of my subject as equally important, therefore all must be in sharp focus. (I like a spray-painted canvas backdrop, that won't look in focus no matter what.)
I believe most portraitists do prefer nice bokeh, and of course your philosophy is as valid to you as mine is to me, I certainly do not imply that mine is right, or best.
My favourite lens for nature and scenic photography is a 105/3.5 Schacht Travegar, on a bellows. Why? 16-18 diaphragm leaves - great bokeh!

Just be careful when handling the camera that the cord doesn't catch on something. Leaving it attached won't damage the camera or release.

I bought a really beat-up F3HP cheap in 1988, as I needed the mirror lock-up that my Exakta VXIIA lacked. Looked like it had been through 3 wars, but I used it for at least 75% of my pictures until the LCD panel died in 1996, then I bought a new F5. I later bought one of the last new F3HPs' made, and use it for nearly all my film pictures (I shoot about 75% digital now). I've only shot 2 rolls with the F5. My other film cameras are Leicaflex SL and SL2.
I used Kodachrome-32 until it was discontinued, didn't like Kodachrome-64 and have only used Fujichrome-50 since. I take nature shots in the mountains and deserts of Southern California, and when I travel light a tripod, a 50~135/3.5 Nikkor, a Sigma 1.4X APO teleconverter and extension tube set is all I need. Other favourite lenses are a 90~180 Vivitar Series I and, of course, the single focal-length Nikkors up to 400/5.6 ED. My close-up lenses include a 55/3.5 Micro-Nikkor and 90/2.8 Kilfitt Makro-Kilar.
Leicaflex SL and SL2 build quality cannot be questioned, but the Nikon F3 will take a back seat to no one. Enjoy.