From New Orleans to the eastern shore of Mobile Bay you can take 90 along the coast, then take 98 once you cross Mobile Bay. 98 along the coast of the Florida panhandle is a very scenic, but slow trip. When 98 turns south and combines with 19 & 27, (in Perry), you are cutting a corner, so it will be almost as fast if you had taken interstate 75, but 19 will be a lot more scenic and interesting. Crystal River might be a good place to cut east, but avoid getting very close to the Tampa-St.Pete area at all costs - the state roads become very congested and slow - taking interstates down there is a necessity. You could take 90 all the way to 27/19, and it would be faster than 98, but 98 across the Panhandle is a real treat.