I recall reading somewhere that the Hudson River Valley is "arguably, the most beautiful river valley in the world". Thought it would be interesting to hear people's comments on that and see how people compare it w/ other river valleys.

No. The Columbia River Gorge beats it hands down!

No question -- the Grand Canyon of the Colorado River is the most beautiful. Even more so than the Merced Valley in Yosemite, the King River Valley in Kings Canyon, and the Green River valley in Canyonlands.

Paul:
With due respect. That's not a river valley but a rocky gulch.

For an interesting perspective on river travel and some remarkably lucid descriptions of river vallies, many accessible only by water, I suggest reading "River Horse", the newest from William Least Heat Moon. He traveled from the Atlantic to the Pacific by river, canal and lake, utilizing a small boat and canoe with only a few short portages. Insightful and humorous as well as erudite - recommended.

Columbia River Gorge is tops in my book. (I don't count the Grand Canyon...not the type of 'river valley' in question IMO).