Flight
Allegiant will have cheaper flights flying out of Chicago Fridays and out of Savannah Mondays if you look about 1 - 3 months in advance.
Flight
United and South West frequently have flights to and from Chicago/Savannah on Thursday evenings. I still recommend to look into the flights about 1 - 3 months in advance. You can go on Google and sign up for email alerts when there is a down trend in flight prices.
Hotel
Hotel
Hotel