Thanks for bringing up Wisconsin Steely, I was going to say that too. Maybe I am just biased having grown up there, but the Wisconsin state capitol is definitely my favorite, especially among the classical domes, I think its got the proportions just right, even better, in my opinion, than the US Capitol.
My favorite part about the Wisconsin Capitol is how it completely dominates the city plan and is visable from just about every part of the city. It lies in the middle of what is essentially a giant four square block round about that has eight streets that terminate there. Here is the original city plan (which was carried out almost exactly as shown) for the city of Madison:
University of Wisconsin Library
The capitol was constructed in the large empty square in that image with each of its wings facing a cardinal direction. The image above is somewhat misleading because the isthmus actually runs southwest to northeast and therefore the grid follows. So really, the diagonal streets in the plan run north, east, south, and west.
The longest diagonal that terminates at the capitol square is now known as State Street and is the primary shopping and entertainment district and also runs directly to the University of Wisconsin. It is now a pedestrian mall (with the exception of buses) that provides for stunning views of the terminus at the Capitol.