We live about an hour from Savannah and it is one of my favorite places on earth with its historic mansions, 21 beautiful squares and riverfront.
A trolley tour would give you a great overview and just riding around the various squares with their monuments, benches, fountains and trees full of Spanish moss is a treat. Forsythe Park is lovely any time of the year, although not much is in bloom until later February or March. I agree with the recommendation for the Old Pink House restaurant--I think it is one of the best in town and I never take visitors to Paula Deen's place--very overated in my opinion. Also don't miss the old civil war graveyard with the "wall graves" and the Cathedral of St. John the Baptist on Harris Street. It reminds me of some of the European Cathedrals. Some of the historic homes are open for tours and the architecture is awesome.
As to the temps, it rarely freezes in this part of GA, but February is our coldest month with daytime temps ranging from the 40's to 50's. Enjoy!
Ava