Florida, and the Eastern part of Texas, are just about as seismically inactive as an area can get, and there doesn't appear to be anything in either location that would generate anything damaging.
Don't have to get too far away (South Carolina, Oklahoma) before you get into areas of fairly respectable quake risk, but there are parts of the country where quake risk is basically nil.
However, in the "lower 48" the largest earthquakes ever felt were likely to be the series of quakes realted to the New Mmadrid fault zone, between St. Louis and Memphis, which occured in 1811-1812. Three earthquakes (foreshocks, shocks, and/or aftershocks) each measuring between 8.0+/- and 8.5+/-. Accounts of the day suggest that overnight part of the Mississippi River flowed "backward" to fill a quake-related graben (depression) now known as Reelfoot Lake (northwestern Tenn). Earthquakes related features, formed in 1811-12, are still recognizable today.