I kinda veered off into stuff that`s not *really* related to the washbay...sorry
Yeah, agree completely..all about *convenience* and making it time/effort-efficient.
The "point source" lighting I have in the shop is just a bunch of hanging incandescents (modern version would be LEDs), which work fine for me, BUT...you don`t want water to hit `em when they`re hot so they stay off during the actual wash. Note I also have fluorescents on the walls; I like, and need, a *LOT* of light and I`ve never had my shops "too bright" yet.
And/but, yeah...have lots of separate circuits or you`ll be tripping breakers all the time (my builder`s original electrician [screwed] that up so badly, utterly deviating from my printed specs, that I tossed him off the property and brought in somebody else).
For a single-car washbay the 30 x 36 would probably be fine. Hard to say since, without having that curtain, I can use as much of the (pretty big) shop as I want as long as I don`t get overspray on the other vehicles. ALthough...that 30" dimension, I dunno...that might be a little tight. Eh, I`m used to *LOTS* of elbow room, like...virtually unlimited...so I`m spoiled. Or at least I was until I,uhm...accumulated...a few too many vehicles
Yeah, the curtain would go/protect any area where overspray would be an issue. For me that`d mean running it down the middle of the shop floor, but that`d depend on the actual building/layout. Those curtains can be pricey! And they require a cable/track/somesuch that might be a bit tricky to figure out just right the first time.
I wouldn`t want shelving anywhere near where I`m actually working as I`d worry about overspray/etc. I just have bare walls (other than the lighting/etc.) with Fiberglass Reinforced Plastic for the lowermost 4`. I don`t need to store much Product around the washbay as I keep my every-wash-products on polypropylene carts (again, one on each side plus a third one for other stuff).
Towels are in big Rubbermaid trashcans (color-coded) on casters. They`re not right there in my washbay, but they could be since they`re waterproof.
The whole idea behind "what`s actually *in* the washbay area" is related to "would I care if it gets soaking wet?". IME, and I`m awfully careful, sooner or later some hose/etc. will fail, or user-error will rear its ugly head, and it *will* happen..everything soaked in a big way.
No need for a heated pressure washer as running warm water through mine has always been sufficient. And I`m using the cheapest/weakest pressure washer from AR and it`s *plenty* for washing cars...and safe on the older ones where I could easily do damage.
I just HVAC the whole building, with zones to direct what happens where.
Hope the above cleared up anything that was fuzzy.