I did this 90-miler for the first time last year. Winds were light but in past years there have been some real struggles. I rode with a team which made it a little cheaper. It goes entirely around Wisconsin's largest inland lake. For the most part it's flat, though there are some minor rollers near the end. There was literally just one sizable hill at the halfway point. I managed just over 20mph average. Winning times were a bit over 27mph. Winners took home over $30k in prize money for individuals, teams, etc.
Riders depart in waves of a few hundred. Elite riders first and so on so less race-experienced riders don't get in over their heads. Stop lights are a non-issue since police take care of that.