harryjacky! I read your post I am sure your recommendation is wonderful for your friends. I want to say that last year I and my friends have visited the Chicago trip. On my trip, I have visited these attractive places. But Millennium Park is my favorite attraction in Chicago. In my trip, I have enjoyed many activities there. These are Cycling, Walking, and Photography. I suggest your friends must visit this park and enjoying these activities there. Best of Luck!