Thanks! I did most of the heavy adjustments in ACR, exported to TIFF, stitched, exported to a layered PSD file, and did the final blending by hand, airbrushing the layer masks. After stitching, I brightened it just a little with a Levels adjustment (tweaking only the setting of the middle (gamma) slider, sharpened, then did a slight hue adjustment on the yellow flowers--they had acquired a slight magenta cast somewhere. There's a trick to what I did with the shadows here. I did a local contrast enhancement using USM radius 250, amount 35, threshold 0, then faded that to 67% opacity. Adjusting a bit past the limits of good taste, and then fading by 33% keeps USM from clipping the highlights or shadows. Even if the USM adjustment itself makes the shadows or highlights block up, you get detail back when you do the fade opacity thing.
I have a couple 12x36" frames. Leaving a 2" border all around the image leaves 8x32" of image area, 4:1. But the original file I cropped this from is 29322x4108, so I could print this 24" high at just over 170PPI. I definitely wish I still had my 7600 right now...