Gene- thanks for the link to Sheron's work. I love it! Makes me want to try color. There is a real grace to her people in the very ordinariness of their lives... good stuff.
Baxter, I can't help with the ND grad filters, as I'm not a color landscape shooter, but it does seem to be a problem inherent with an RF system. My only advice in that regard is the old tried and true method of trial and error.
I've had my Mamiya for about a year and a half, and it took me awhile to really get used to the focussing, and the framing. But I was just so pleased with the negatives, that I kept at it. I used it a lot this past summer and fall, and hope to get a lot of prints done this winter! With all that said, I'm glad I stuck with one lens for so long, as a result, I'm now very comfortable with the camera, and I feel ready to add some extra lenses.
I decided to get the 150mm for the moment, and the close up attachment, which may come in handy for these still lifes I have in my head, that I'd like to commit to film!! The 65mm, I decided, could wait since it's so close to the 80mm. When we are feeling a bit more flush with cash, that'll be the next lens, though! It looks like an excellent focal length for the Mamiya7, and, I expect, for just about any medium format RF camera. The other two wide angles, the 50mm and 43mm, I think may be too cumbersome for my type of shooting with the second hot shoe view finder.
Thanks for all the informative answers.