Sorry, I've never been to the Smokies. But I'll put in my 2 cents worth anyway.
Moon.com has a series of guidebooks for hikers and tourists. The former used to be known as Foghorns Guides. Since they cover large areas, they are not comprehensive. But they do list the authors' favorite hikes.
Since most of my hiking is local (Norcal), I purchase guidebooks that include the Natural History of the area. But if I wanted a guide to hikes in another part of the country, and my vacation time was limited, I'd go with moon.com.