I played the Straits and Arcadia within the span of a couple of weeks in May/June.
I agree with Cary, both courses to me were fabulous. Manufactured and over the top yes, but they're not trying to disguise that part, and both architects to me did a great job of making the courses scenic, challenging, yet playable under different conditions. I scored much better at Arcadia, but it was a calmer day and from a shorter yardage.
I liked Whistling Straits a little better because I felt like the course did a better job of ending with some of the better holes with the exception of 18. Under the current routing to me almost all of Arcadia's best holes come in the early/middle portions of the round. I'd go back to either one. I personally liked Straits #17, but I thought 18 was over the top, especially at almost 500 yards! Maybe that was the intent however.