You can put a workpit in, but at least for commercial construction, it has to have an alarm system and sensors to detect harmful heavier-than-air gasses that could settle in there, along with a ventilation system. May not be worth the expense.
Gotta have at least one washbay with a drain, and floor sloped to it. I'll say for us, a curtain would be enough. The extra cost of a wall could be better spent elsewhere because we wouldn't use it every day, and the curtain gives you flexibility. Depends how big you are though and how much you'll use it. If you use an open drain style with grating (as opposed to U-drain with a narrow opening), make sure they use heavy grating that can be driven on.
Gotta have exhaust fans for the washbay, I'm a stickler for safety and air quality so I would try to find a cheap exhaust hood setup for welding too.
Infloor heat is great but pricey and I'm cheap, we might just lay lines under part of the floor and jimmy-rig a water heater to use on occasion, with radiant tubes to be the main source of heat. Need to see how the dollars shake out.
Some will put infloor heat lines in the outside slab and at the concrete where the overhead/bifold doors sit, I think that's a good idea but set up so you turn it on only when you need to.
Most won't insulate at the edge of the slab / outside face of gradebeam. New energy code takes care of that but farm buildings aren't required to conform to the energy code; I'd still get my builder to do it, or do it myself.
Here's a good one, a pit for changing oil. The setup I saw, he had a pit you drive over, pull the plug and let oil drain into the pit. There was a line to an above ground tank outside with a pump, so you turn a pump on and it sucks from the pit to the tank. Nice and clean. I think the pump was set up so you turn a couple valves and pump out of that tank as well.
Put some thought into orientation and which way the doors face in relation to prevailing winds. You don't want to be clearing snowdrifts in front of the main overhead/bifold door.
If you're building a heated shop but could use some more cold storage as well, it would be cost-effective to build one building that's part heated shop, part cold storage.
If money is no object, skip the pole sheds and stud framing, build a pre-engineered steel building.