The hostel mentioned above is in a very good location for many well known Chicago touist attractions. You can walk to the Art Institute and the Museum Campus from there. You are also close to the Sears Tower and Millennium Park. The high end night life and shopping are a little farther away (to the north), but not too far for 5 young people. I have not stayed in the hostel but have passed by it many times. It seems bright and safe - and is undoubtedly inexpensive in comparison to most other options you'll have. It is also located near several downtown universities which means there will plenty of other people your age nearby.