Hey Bill, good to see you posting again. I bet the North Rim is nice that time of year, although I can't image how cold it must be at night, I'd definitely want to be camping in a trailer not a tent.
All of these are nice, but the second one really does it for me. Beautiful colors, I love those warm pastels. The light is very soft, but still directional to show the contours of the canyon well. The lighting in the last one is a bit more dramatic than the second, but I prefer the warmer colors. The first shot looks like it might be a good candidate for B/W conversion.