While I consider myself a lifelong resident of SW VA I will concede this: Roanoke/Salem/Vinton could be considered both (equally) a part of SW VA and the Shenandoah Valley.
Heres a map of SW VA
Heres a map of Shenandoah Valley
Roanoke is included.
However in this map, Roanoke is not:
(The kicker is, both maps are official government maps! LOL)
It just depends on who you ask, which is why I can see why Richmonder27 considers Roanoke as part of the Shen. Valley. Its all in who you ask.
The basis of the Shenandoah Valley is the Shenandoah River that runs through the valley. If you judge by the river, Roanoke is not within the broad Shenandoah watershed so it would not be considered as part of the valley.
Or, you can look at it as geologically lying within the valley of mountains that make up the valley. Geologically Roanoke is not part of the Shenandoah Valley..
That leaves the cultural aspect. Culturally, Roanoke is sometimes classified as Shenandoan. Im not sure I necessarily agree with that; I would argue that Roanoke is significantly culturally different than, say, Harrisonburg, Waynesboro, Staunton, Winchester, etc.
However, many in the Roanoke region would probably self-identify as Shenandoan (think Shenandoah Life Insurance based in Roanoke)
Then again, im not a cultural anthropologist so Im sure whoever made the assertion that Roanoke is Shenanadoan knows a bit more than me.
So it just depends on what you're going by and who you ask. Neither is right or wrong, etc.