It's a quick walk from the Hyatt Magnificent Mile to the Gleacher Center. Head out of the hotel and walk west on Ontario Street to Michigan Avenue. Turn left and walk south to Pioneer Court at the Tribune Tower and turn left. When you reach Cityfront Plaza, turn right and the Gleacher Center is on the right.
Conversely, you can walk south down St. Clair Street and when you encounter stairs, take them up to Upper East Illinois Street and continue walking south on Cityfront Plaza to the Gleacher Center, which is on the right.
The Gleacher Center is located at 450 North Cityfront Plaza Drive.