Thank you all for your thoughtful suggestions. Here are my thoughts and more information:
Bullfrog: While I've heard that color space can be an issue with Photoshop, to my knowledge Lightroom uses an internal color space that is not configurable. And as I'm printing directly from the application, I don't think it's an export issue.
Chris: I've tried several different calibration luminances ranging from 140cd/m2 to as low as 85. I do wonder if there's a monitor setting I don't understand somehow because the luminence differences I observe in this range are not dramatic. The Spectraview II software purports to write directly to the monitor LUT and I'm not fiddling with the monitor controls, though, so... I've also checked the prints in direct and indirect sunlight and the problem remains. Not that it seems pertinent, but I've also tried several different color temps (5000k - 6500k) and contrast ratios (settled on 300:1). I agree that the "Capture to Print" series, which I've watched as one of the steps I took to try to solve the problem, is excellent. Unfortunately, I wasn't able to glean the answer from there.
mcbroomf: It's been a while since I printed on other papers but my recollection is that the result was the same. I'll check it later today and repost if there's a difference. Thanks for the thought.
howardm: That's an intriguing thought. I have a friend with the same monitor but different calibration software and hardware who doesn't have this problem. I'll see if I can borrow his puck, though it's actually older than mine (6-7 years old) by a couple of years. Do they really fall off that much?
Thanks again, all. I'd love to hear any other ideas you may have. Greatly appreciate the assistance.