Ive been to SAV a couple of times, didnt stay at the Westin or even DTown. I stay in the MidTown area were there arent any FS Hotels.
However keep in mind that The Westin is Not located in DT either but is a bridge drive away (dont know its theres a toll or not), or if the Hotel runs a shuttle., but it is isolated but I believe comes with a golf course.
If you want to be in the Downtown area and want a FS Hotel, you have Double Tree, Marriott, Hyatt (probably the nicest there and right on the River) the Hiton is a good few blocks inwards but in the middle of The Historic District, also theres a Hilton Garden Inn. Here and there you will find some Hampton Inns and a Courtyard-Marriott