I normally got the GSM area a few times a year. I have been there pretty much everytime of the year.
As for the park roads, they even close the main roads through the park if there is any chance of snow or ice. Too risky. Also remember that the main road through the park (441) will rise about 5,000+ feet. They have a habbit of closing it a lot in the winter months due to wind, snow, and ice. The alternate route sucks, (2.5 hr drive vs. 45 minutes from Gattlinburg to Cherokee) so don't get stuck.
As for places to see, most have been listed above. But above all, GO SEE THE PARK. Just beautiful sites and a fun drive. Also, the aqurium is great if you have kids. Tuckaleechee Caverns are also a great visit.
Places to eat, well that could take a while. LOL Skip the Peddler or Park Grill. Over priced, crappy service, and the food really isn't that good. You want a steak, go to The Alamo. Also must stops for good food: The Old Mill, Smoky Mountain Brewery (great wings and beer), The Apple Barn, Pancake Pantry (get there early or through the week).
Also I woud suggest skipping Dollywood unless you have kids around the age of 8-15. It is not compareable to Kings Island or Ceder Point. More family friendly. If you want a good dinner show, I always suggest the Dixie Stamped. Yeah corny, but fun if you have never been before.
Let me know if you have any other questions.