Make it too fancy and it will get invaded! You can be sure. Too fancy and the wife wants to horn in and bring her friends out. Kinda nice and your friends will sniff it out and be over every night to watch the game and drink up all the free beer or to get away from their wives. Makes no matter that you'd planned on reloading or kicking back and reading a book. Been there, done that.
If the shop is attached to the house, your wife will use it as a dumping grounds for anything she doesn't want in the house or doesn't know what to do with. This means every time you walk into your space, you'll trip over or walk around a pile of crap that has to be dealt with before you can do whatever it is you want to do. Been there, done that.
I'll tell you what I have now and maybe you can use some of it and throw the rest away. It's similar to what I had in Oklahoma. 16'x24' free standing building. A/C. Wired for 220. No phone. Cell phones don't work in my little holler and since I'm now a widower, I only get calls from old women looking for a husband and telemarketers anyway. No windows because they take up too much storage space and why let the robbers in? I do have sky lights in the roof for natural lights. Sturdy work benches, shelves, and peg board around most of the walls. Plug ins at every stanchion of the work bench. Under bench storage. I have things like grinders, chain saw sharpeners, and such that I only need occasionally mounted on boards and stored under the benches so I can take them out and bolt or clamp them to the benches only when I need them. Fluorescent lighting over the benches. A couple of mounted vises. I've got a small micro wave and a Mr Coffee. I have a dorm sized fridge with a few pop and a jug of water since I don't have running water. No beer since I don't like to use drink and use power tools or reload. In the center of the room, I have a pedestal gun cleaning station. It's was some sort of roll around kitchen work station that I took the wheels off. I have a gun cradle on top; I put my cleaning supplies in the drawers and hang my cleaning rods down the side in a gizzie I fastened there. It has a fourcent light over it also. Having a dedicated gun cleaning station or gun working-on station is the greatest thing since bottled beer. Especially one that you can walk all the way around. The work station is big enough that you can sit things around the cradle and not worry about them falling off and such. Its wired for electricity and also has an overhead plug in. If I glass bed a rifle in the winter, I can plug in a heat lamp and hang it over head as I heat the shop with wood.
At one end of the shop, I have a wood stove with a heatalator fan. An easy chair, foot stool, and a reading lamp. One straight back chair. If I have more guest than that, they sit on up-turned 5 gallon buckets or milk crates.
At the other end of the shop, I have a loft that I use for storage. Under that I've boxed in a room that is used for reloading. Nothing else. Separating the reloading room from the rest of the shop, I've hung clear curtains that I can close if I'm doing anything in the shop that might create dust. I have two reloading stations on a very sturdy reloading table. Both presses are mounted on 1" plywood which is mounted on the reloading table with carriage bolts and wing nuts. They are mounted so they overhang the edge of the table by about 2". The bolt patterns are so they can be changed about. One is set up for small rifle and one for large rifle --I don't reload pistol. I have another, same bolt pattern, that I use for my target ammo. I guess I could mount it also but IMO that would make things too strung out. My other stuff, like case trimmers and such, I mount on boards and clamp them to the bench when I need them and put them on the shelf when I don't. I like a uncluttered work space. My powder measure is mounted on the wall at one end of the bench and I would set up my Ohaus 10/10 in front of it. I use a Lyman 1200 now. All of them go on the shelves when not in use. I have two gun safes and a large metal cabinet. I keep shells, bullets, random stuff in the cabinet and valuable stuff in the safes. I have a comfortable roll-around chair that I sit in to reload. If someone wants to watch me reload, they can bring in the straight back chair or sit on a up-turned 5 gallon bucket.
I have motion detector lights around the outside and three 1/4"x3" straps acrost the substantial door with substantial locks with ONE key. And that key is in my pocket.
If the guys want to come over and drink beer and watch the game, we go in the house.
My late wife didn't put too fine a point on it: the first time we got crosswise and I went to the shed, she started calling it "John's pouting place".
Sorry to run so long. One thing a I would suggest, start you a folder and every time you get an idea, write it down and drop it in the folder. Somewhere along the line, get you a pad of graph paper and start drawing some of it up incorporating the ideas you have.