There is a ton of good advice here. I adapted a three bay garage plus breezeway plus 12x12 annex as shop, lab and motorcycle parking (the breezeway). What worked out well is three 10' wide sliding doors, arranged so any one can be opened (but not more than one). This has given great flexibility for moving equipment and material in and out. While you're laying out the slab, provide for an outside compressor, maybe in a room or covered area. This is so much better than a compressor inside the shop. Might be a good time to plumb for air also.
I made a kind of lean to roof along one outside wall for sticking wood, etc.
While you can't have too much power, for a personal shop it's easy to overdo it. I'm pretty limited to a 50A 220 service, and it's been plenty for any operation I've encountered. Wintertime I run a couple overhead infrared electric heaters, and I can operate any one tool and the compressor, along with lots of LED lights, some power hungry computers, monitors, etc. with no problem.
I sure wish I had water and a drain, but it's not worth the trouble. There's a hose bib right outside the shop and it's 60 feet to a house bathroom with an outside entrance...seems farther sometimes.
Good luck, enjoy the process!