A long, winding observation from the region... may be of help, may bore you to tears.
1) Your coal mine should probably be past a mountain ridge, and on a hilly plateau, since the rich coals seams are not on the mountainous Allegheny Ridge, but rather on the hilly Allegheny Plateau. A lot of the challenge and drama of the classic coal RRs - N&W, C&O and their forebears - had to do with getting over the ridge hump and past that to the coal fields beyond. There's no significant coal on the eastern side of the Ridge.
2) Just another geographical note: the Blue Ridge and Allegheny Ridge are two separate ridge lines within the Appalachian system, with the Shenandoah Valley in between. Both ridges were engineering challenges to RR builders, and there's a lot of history there, with interesting grades, tunnels (Alleghany Tunnel west of Covington, Va), switchbacks and the like. The RRs often snake around the narrow meanders of rivers in order to break through the mountains up and over to the coal fields on the Plateau. Classic Allegheny railroading. To have these snaking lines adds running length for a small MR area! Check out the RR lines on a topo map of the region - DeLormes (sp?) - or Google Maps.
2) Used to be an iron industry in west-central Va til the mid nineteenth century, until better deposits were found in the upper Midwest. Va place names like Clifton Forge, Longdale Furnace and Iron Gate attest to this. So, if you are earlier in history, or if you like to freelance...
3) Paper Mills. Paper mills are really significant in the area. Lots of rail traffic, and one of your best bets. There is a huge Westvaco plant in Covington, Va, look it up on Google Maps. It's the biggest employer in Alleghany County, replacing the railroad (C&O) that once dominated the region. Interestingly, woodchips now come into the plant by rail from east-central Va, via the Buckingham Branch shortline. So the rail traffic is nicely two-way, east-west.
4) Limestone quarries. Lots of big limestone deposits on the eastern side of the Allegheny Ridge. It's Virginia's second most important industrial mineral. And there is actually an underground limestone mine in Southwest Va! Lots of open quarries. Lots of limestone crushing and processing too, for industrial purposes. Served by rail. There is also harder rock quarries, making, among other things, railroad ballast. To the north end of Va, outside of Winchester, there is a quarry at Gore, Va, which is the essential remaining reason for the old Winchester & Western short line.
5) In the Piedmont, on the eastern foothills side of the Blue Ridge, the fruit and canning industry is big, and there are processing plants served by rail. Not served by rail, but a possible scenic element are the vineyards speckling the Piedmont. Virginia wine is fine, and it's a big growth "industry" in the area. Over the Blue Ridge hump, in Buena Vista on the western foothills of the ridge, there is a school bus manufacturing plant. If you kids take a Blue Bird bus in the morning, might be from BV, Va.
6) An important industry is rail servicing! Cities like Roanoke and Lynchburg were built by rail. Roanoke was the center for the old N&W, which essentially started the city. They still have a big NS servicing yard there, a major employer. Lynchburg is the nexus of NS and CSX lines, and has lots of rail-serviced smaller manufacturing.
7) The Shenandoah Valley is booming, especially to the north around Harrisonburg. The poultry industry is huge there, and serviced by rail for poultry feed. The animal feed industry itself is big, with both inbound (poultry feed) and outbound rail of agricultural feed. There is also a big Coors brewery serviced by rail, as well as auto parts manufacturers. A big fertilizer plant. Lots of small manufacturing too, such as plastics and metal fabrication. There are also very large offset printing plants in the Valley, a good destination for the Gunderson cars from your paper mill.
The Shenandoah Valley is booming so much that there is a controversy about truck traffic on I-81 up the valley. NS is being pressed to increase rail traffic on its valley lines, and improve the rail and maybe even add to the mainline. You'll see more intermodal running up the Valley to points beyond.
There are also cabinet making plants spotted throughout the north Valley (and Piedmont). Kitchen cabinetry...Merrilat and American Woodmark, for instance. They could theoretically be served by rail. Try cabinet makers instead of generic furniture factories.
In northeastern WVa the poultry and feed industry is also big, and a major reason for the state-supported South Branch Valley RR shortline, which winds down the south branch of the Potomac. Former C&O line. Google Petersburg and Romney WVa. Also have plastic plants in that region which receive pellet hoppers.
8) A lot of the counties that border Va/WVa on the Allegheny Ridge are very rural and beautiful, but without a lot of industry. Logging as a big rail-served industry has played itself out, though there are scenic railroads running on those old lines. But to be realistic, the cross-border action is between the coal fields, through the scenic mountains (with perhaps a quarry or paper mill), to the Valley, Piedmont and Tidewater beyond, which is where all the industrial-style traffic is.
Bear in mind that southwest Va coal is in decline, and WVa coal shipments ain't what they used to me. The economy of the coal areas is not in good shape, though they are trying to diversify. Modeling abandoned mines near active ones is highly realistic in this day. Unfortunately, a lot of the active West Virginia mines are strip mines or mountaintop removal mines (not going to touch that one again!)
9) This need to diversify is driving reason behind the interesting Transdominion Express (TDX) rail proposition, a passenger rail system spanning Va pushed by Southwest Va politicians. I don't know the state of play of the politics and budgeting for it, but it's proposed hub is Lynchburg with major stops in Charlottesville, Richmond and on through to Washington, DC. They're talking about using NS lines, and some CSX if I recall. If it comes about, it will be a major passenger rail project, and they will use luxurious passenger cars. They actually have a web site for the project. So if you're a free-lancer, you can get a jump on the project and model it if it's reality or not. They'll be upgrading or creating stations, servicing centers, etc.
Hope that's not too much, and sorry for swamping the thread . I guess I've been spending too much time learning about rail in Virginia and the southern Alleghenies. Guys, come railfanning to Virginia - it's a great railroad state with a rich history!
PS...(further) trivia note; In Va and NC, we spell it "Alleghany", instead of "Allegheny", which is common in WVa. Alleghany was the colonial English version, while Allegheny was the colonial French spelling, and adopted in the north. To make matters more complicated, Maryland often spells it "Allegany
