My advice would be stay with the 10 ft room and put in a cleaning area right in the middle of the room. This way you have a good area to work on for cleaning.
Now on the benches, make them super solid. There is no such thing as too strong of a bench for reloading. I would also keep my benches about 30" deep and put in a lot of lights. I would run a continuous double bulb fluorescent lights around the perimeter of the bench about 24" off the bench surface so you have decent lights. I would then put in 8' fluorescent fixtures on 36" spacing perpendicular to the long axis of the room. I believe there is no such thing as too much lighting when reloading.
Beyond that walk it out a few times and really think it out.
I agree with Jim Kirk! And with Peter Eick on all points except the 30" depth! Two reasons: I'm short and 30" puts me too far from all my upper shelves, especially the higher ones. Second, I prefer all my stuff above me, visible, yet out of the way. With a 24" bench you are not as tempted to clutter it all up. ( Of course Peter's published pictures of his bench shows NO clutter...that's either amazing or staged...Peter?
Below is my anti-torsion beam bench design that I use, which provides a super solid, immovable beam to mount your presses (using 6 inch carriage bolts to anchor them through the solid beam.) The advantages to this design is the ease and speed of building, minimum lumber cuts, and need for only 3/4" plywood top. The top doesn't need to provide any stiffness to resist torsion from the press strokes, because the beam does that. Don't bother cutting cross supports except at the ends. Totally not necessary with a 24"-6" or 18" span and the torsion beam and way less work!!
Provide plug-ins below your bench and cut "computer desk style" holes to access them...that keeps the cords mostly off your bench. When you mount your presses, use a fender washer (big washer, little hole) under the beam that will span between screwed and glued members of the beam. Even Peter would be impressed with the stout immovable bench this makes. BTW, the back 2x4 is screwed to the wall with 3" cabinet/deck screws, and legs can be spaced 8' apart.
Notice that you really only need a braced 2X4 leg (the tall 2X4) braced with the outside 2x4 screwed 90 degrees from it. (the other members in the front of the leg detail are only window dressing I added later to make them look massive and impressive. The quarter round hides the joints and makes it look like one big carved leg...you actually need none of that unless you wish to impress your friends.
I'm a building contractor...for me it is advertising.
On the subject of fluorescent bulb color...
Quoting from Wikipediea: "High CCT lighting generally requires higher light levels. At dimmer illumination levels, the human eye perceives lower color temperatures as more natural, as related through the Kruithof curve. So, a dim 2700 K incandescent lamp appears natural and a bright 5000 K lamp also appears natural, but a dim 5000 K fluorescent lamp appears too pale. Daylight-type fluorescents look natural only if they are very bright.
I experienced both in my reloading room. High CCT light is way superior
IF you have enough of it. It reminds me of being in a depressive Sci-Fi movie if there isn't enough. I have tried mixing them in my 8' strips, and that works better. Or double them and use 5000 region "natural daylight" lights.
