I would have been perfectly happy if all of Mac 'n' Cheese was in Door county.
I am not sure the 600k loop has much appeal. OTOH, the Catskills 600k I mentioned above was a loop, and there really was no appreciable difference between that and one that returns to the start for the overnight. Actually, on that route the start/finish is not in a good area for cycling, so not going back there was a bonus. I am not convinced that a 600k prepares people for PBP, I know it didn't help me much. Same for night start 200k's. I had ridden 4 600k's before PBP and the whole thing was a shock. Except for waking up after riding 400k, that I had done before. What I wish is that I had ridden a domestic 1200k before I went to France.