I live on the south side of Milwaukee, and commute through downtown up to the north side/suburbs.

Like someone else said, it's not crowded, but there are a fair number of other bike commuters. Which is great, because by and large drivers here are more (or at least seem to be) aware of cyclists on the road.

On my ride to work in the mornings I usually see five to seven "regulars" heading downtown on the MUP, their commute being opposite of me.