Thanks for the tip. Reminds me of the old joke "there are two seasons in Wisconsin: winter and road construction."
During the short time I lived in Milwaukee, coming from downtown I usually got off I-94 at eastbound Howard Avenue, then made a right on Howell to get to the airport. Howell has pretty light traffic and it's a mile or so shorter than staying on the freeway, going around the Plainfield Curve to the Airport Spur. Even without construction this route seemed to be about the same timewise as taking the spur.
Coming from the south and west I nave never found a very good alternate route, especially with all the construction on 894 and 94.