There's several wineries in the Smoky Mountain area including a dense area called "Rocky Top Wine Trail" which consists of 3 wineries within 3 miles (Hillside, Apple Barn, & Mountain Valley Winery). In this article, I'll compare two of them vs. Mountain Valley winery.
Overall, I'd suggest including a winery as a portion of your Smoky Mountain schedule. When I've traveled through wine country in Sonoma, CA or eastern, MI, you could fill the whole day happily wandering through grapevines and visiting wineries. However, in the Smoky Mountains, I'd suggest you get outside and perhaps visit one or two wineries as a romantic ending to the day. Therefore, I'd suggest being choosy in which ones you visit.
I recommend Smoky Mountain Winery (Gatlinburg, TN) over Mountain Valley Winery or Hillside (both Pigeon Forge, TN). While all had nice regional sweet wines, the real difference for me was the level of service. At Smoky Mountain Winery, the lady gave me a warm welcome and gave me her full attention. With such service, I was able to overlook that the samples came in a shot glass instead of a wine glass and have a conversation about the wine. At Mountain Valley Winery and Hillside, no one even greeted me and it felt like they were really set up to crank through the tour buses and take orders. Smoky Mountain Winery tasting room is much smaller and I think you'll enjoy the quaint atmosphere and service.
After I made my assesment, I searched online to see other traveler's viewpoint:
Smoky Mountain Winery:
Wine: Specialties in sweet wine; I chose the Muscadine Red
Price: Entry level approx. $15
*Service: Consistent positive ratings, criticism on service seems to be the outlier
Example quote on TripAdvisor "The people are so friendly and helpful. They are personable and outgoing, just like Tenn. people are supposed to be."
Example quote on Yahoo Travel Guide.com "My husband and I do a lot of traveling but we have never been treated like we were at home like in this winery"
Uptake.com Tourist Review Rating: 6 reviews, 100% recommend
Mountain Valley (Pigeon Forge)
Wine: Specialties in sweet wine; examples - Rhubarb, Mountain Peach
Price: Aprrox. $15; examples - Blackberry $15.49, Mountain Valley Blush $13.49
Service: Inconsistent, seems dependent upon the host, shout outs to Kevin & Doug
Example negative quotes on Trip Advisor: "Beautiful shop, great wine, but the staff members completely kill it"; "Worst service ever...we walked in and no one acknowledges your presence."
Example positive quotes on Trip Advisor: "treated like family and wined like royalty"Uptake.com Tourist Review Rating 58 reviews, 75% recommend