I'm a Michigan guy, and irretrievably prejudiced as a result. I also happen to be a huge fan of C & C.
When Tom Doak gave the U-M course a 5 in his Confidential Guide, the U-M course was in a state of moderate disrepair. It had hosted a couple of Michigan Opens, but it had suffered from three big things: 1) Badly irresponsible tree-planting, 2) Terrible maintenance of its Mackenzie/Maxwell bunkers and 3) Generally poor maintenance of its green surfaces.
The Arthur Hills work that was undertaken a couple of years after The Confidential Guide was published was much needed, and was generally regarded as a 'restoration,' and not a redesign. Hills cut down hundreds of trees, as he should have. (They could cut down a hundred more.) Hills also gave primary attention to the bunkers, which now look 100% better and much more Mackenzie-like than ever. As someone else has noted here at GCA, the spending ratio for the multi-million dollar restoration program was 50% improvement and 50% maintenance. The greens are much better surfaces now than when Tom Doak gave it a 5. And, almost nothing was done with respect to any re-shaping of the unmistakable Mackenzie green complexes.
As a real, true Alister Mackenzie/Perry Maxwell signature piece, the U-M course is a treasure for any student of architecture and it is now a very credible test and an attractive place to play.
The Ohio State University Scarlet Course was designed by Mackenzie within a year or two of the U-M course. The Nicklaus design work there (undertaken gratis by Jack) was by all accounts more of a redesign. Jack changed some angles, wholly redid many bunkers, and consciously tried to make the course more of a NCAA and Nationwide Tour challenge than anything undertaken at Michigan. What is left of the Scarlet Course is a very good golf course, but indisputably a "less Mackenzie" design. Nicklaus famously referred to it as "Nickenzie."
The Warren Course in South Bend is built on a more modest parcel of real estate, and is a fairly unambitious effort on the part of C & C. My feeling is that the great calling card of C & C is to first do no harm to the land that they are given. They excel at that task. And they have created a very good golf course for Notre Dame. But it is one of the most unremarkable of the C & C designs that I can think of, and it is a very cautious, very conventional design. "Solid and unmemorable" is how I'd refer to it.
Someone mentioned the Pete Dye-designed Radrick Farms Golf Club in Ann Arbor. It is the faculty and alumni golf club (University-owned, but basically operated as a private club) laid in the late 1960's as one of Pete Dye's earliest course designs. Set on the old estate of the family that donated the Matthei Botanical Gardens on the far eastern outskirts of Ann Arbor, it is a very beatiful setting and a design that Dye himself happily went back to about 20 years later and revised. I think it is a very good but not a classic design. I find it interesting because it was a remarkably good piece of property (very, very large acerage) and Dye did not have to resort to too many of his later-signature touches. You won't see many railroad ties, and thankfully few severe greenside slopes. There have been one or two USGA championships contested there (boys' and girls' Juniors, I think) and it is a pleasant place to play in the fall, with beautiful hardwoods all around.
Incidentally, the University of Michigan Golf Course was the scene of the first-ever USGA Junior, in the late 1940's, and a 17 year-old from San Francisco named Ken Venturi played in the final match, finishing as the runner-up.