I've been told that they are only passing through the harbor. They are going in the the north entrance and out the middle entrance. Then heading back north a couple of miles. I'd get a spot in the harbor. It might be rougher because of the wakes reflecting, but it'll be smoother because you won't be the open water. Plus you can still head up river if you so wish. Parking suggests that you won't be boating. If so, then there is a new park just outside of summerfest right on the water. It'll offer the perfect location for watching the races. Another spot would be from the Old art museum. The problem is that everybody will be there and you may have to pay admission.