Semi-formal! Wear something dressy but comfortable :) don't you DARE wear white
There is an hourly parking garage beneath the Hilton/Madison Club. Per day = $25
The Dane County Regional Airport is convenient but pricey, and less likely to have direct flights to/from your home. There is not currently a shuttle available directly to the Hilton; using city buses or rideshare services is recommended. Milwaukee Mitchell International Airport and Chicago O'Hare International Airport both have several bus options to Madison. The bus will take about 2hr from Milwaukee, and average 3hr from Chicago.