There are lots of options around Grayson Highlands in SW Virginia. It’s been a few years since I have been up there but I seem to remember the loop using the AT and the Pine Mountain Trail to be pretty easy and very scenic.
The AT from Roan Mountain (Carvers Gap is the road crossing on 143?) to US19E crosses Roan Highlands, which is very scenic and not too hard. There is a Hostel/BB about a quarter mile from where the AT crosses on US19E (Mountain Harbor?) which is a safe place to park, as the trailhead on US19E used to be known from break-ins. They will also shuttle you for a reasonable fee.
I think it would be hard to beat those two for low effort high reward hikes, but here are a few others, that are nice, but not quite as high reward.
The AT from Newfound Gap to Pecks Corner and back. This is a nice ridgewalk hike in GSMNP, it passes Charlies Bunion, for a spectacular view, and since Newfound Gap is high elevation, isn’t too hard. You stay in a shelter, which could be a positive or a negative depending on the person. As you know shelters are more social and can have mice, but some feel like they are more civilized then a tent. One of my wifes favorite backpacking trips was this trip we did together in the mid 2000’s, which was one her first trips with me. Permits and Shelter Reservations Required for this hike.
Standing Indian Loop – It’s a loop, which is nice, and not easy to find on the AT. About 12 miles per day, with a shelter at the halfway point that you can either stay in or set up a tent at. It has Albert Mountain Fire Tower, which has a nice view.