Just a heads up, Savannah is not ideal if you have difficulty walking. A lot of people take the trolleys, but the steps can be difficult for elderly or people using a walker. Also, you may have to walk a distance to get to various sights.
Things may have improved now, just make sure if you do a trolley tour that you double check if they really can accomodate your mobility.
If you use a wheelchair, there may be historic cobblestone streets or brick pathways to navigate. It's certainly possible, it really depends on your level of comfort. This page
has some good reviews of wheelchair accessible places in Savannah.
For hotels, you might try something like the Hilton Garden Inn Savannah Historic District
or the Hampton Inn Savannah Historic District
. There are a lot of hotel choices, so it depends on your budget and where you want to stay.