For waterfalls, great wildlife and great vistas, Smoky mountains National Park is where I generally end up...or in that area at least. If you want to specifically hunt for waterfalls, there are tons of them near Cherokee, NC (this is the area almost all of my waterfall photographs come from). Driving a section of The blue ridge Parkway is always a good choice as well, (Ive only driven the portion of it that runs through North Carolina but it didn't disappoint)

Further south...St Augustine, FL is an obvious choice for architecture, lots of really neat buildings, and just as many great little restaurants to eat at.
A lot of people like Savannah, GA but I haven't spent enough time there to see the attraction