I went through this when we built a condo about 7 years ago. My wife let me design the basement, with the understanding we had to have a bedroom, bathroom, and family lining area. (Her office is inside the family lining area, she is self emp decorator).
We also agreed we wanted a goodly storage area and a hobby/work counter for her.
I wound up with two area's adjacent to each other, one an 8' x 20' workshop with work bench's down each side, and some 36" inexpensive base cabinets covered with 1/2" industrial grade board. The shop includes a 10" sliding compound miter saw, drill press, bench grinder, 1" belt sander, and tool bench with vice. It lets me handle most all projects I have needed to do.
The second "shop" is my loading/gun room. The access is a exterior grade steel door with dead bolt, and cross-bolts out the back edge of the door mating into the door frame. The vault is a 4'X 7' all concrete (poured at time build) in one corner. It has a steel door with dead bolt and cross bolts on the back edge. The interior is wired, with overhead light (a 100W daylight cfl bulb is plenty), and electrical outlets. It is framed up, insulated, and dry-walled. I built up the rifle rack base 12" off the floor for ease of access, and it is full length 7', with the upper rack barrel notch every 3 1/2" (it isn't completely filled yet). In one end I bolted two 15" deep top cabinets stacked to hold handguns and misc such as holsters etc. then I put in two handgun racks on the wall above the rifle rack. The handgun racks are a 4' 2x4 sanded down and clear finish applied, then I drilled holes with 5 degree upward pitch every 3" the full length of each. I used 1/8" brass rod for the 22's and 1/4" for all the 32, 38/357, 9mm size, and 3/8" for the 44, 45 caliber. The brass rod for the .22's I left alone, and the aluminum rod (couldn't find brass at the time) I dipped in the plastic coating you put on tool handles. All the handguns are stored barrel into the holding rods. Looks impressive, with a few dozen handguns lined up side by side. Some of the long barreled handguns and target guns with red dot sights I keep in the wall cabinets.
The loading room work shop is 36" counters in a "U" shape around the rest of the space, (total overall 11X 21"), with work counters over about 30' with base cabinets under for support and 1/2" board topped with 1/4" tempered masonite and give three coats of a clear epoxy finish. I have three loading stations set up and gunsmithing area. I put in a drop ceiling with 3 4' florescent lights. I have a TV mounted up in the one corner, and a nice comfortable chair as well as a counter height rolling work chair.
On the back short wall outside the vault I built in shelving to hold hard gun cases, rifle rests, etc. on the wall opposite I build a rack to hold all my fly rods/ fishing rods.
If I can be of any other assistance, PM me.