My feedback will be similar to the others, but here we go...
What I would first ask yourself, is what type of detailing will you be primarily performing? Production? Or show-car? We all know those differentiate considerably, and knowing what your primary focus will be will only help determine your layout.
First things I would address - white walls, white ceilings, white floor. The way light reflects/refracts off of white will allow a significantly more amount of light to consume the space, rather than being absorbed otherwise. Not only this, but it adds a professional appearance and a 'clean' environment when kept up so. Possibly upgrading the lighting to a more appropriate kelvin / temperature if required will also help with inspections and overall working efficiency within the space.
Second item I would look into is how you feel you will use the space. I feel that, for most applications where you are doing more refined detailing, there is no issue having more than 1 vehicle in a space at any given time. Having a dedicated wash section is a fantastic way of separating the cleaning from the detailing, and I feel there would then be no reason the detailing studio could not be multi-purpose. However, as others have mentioned, take into consideration the work you will be performing and that the space has adequate ventilation to lessen the amount of air contamination. One thing to possibly look into is retrofitting the walls with a PVC-based material that has a natural static charge, and therefore will attract airborne particles to it.
For materials, I think this is something that can be changed over time if necessary, and shouldn't be as worried about as making the space into an ideal, efficient, professional environment that will accommodate the type of detailing you will be performing. Having clean, mobile carts for materials is a great start, and I would even consider having the materials at the 'front' of the shop, so as it can be either a shared bench & cupboard type area, or where each person performing work can have their own / preferred materials stored as so.
Clean Pickup Space - Just as important as the working environment is, you also want to ensure that when a customer drops off & (moreso) picks up their vehicle, it can be displayed in such a way that it reflects the work performed. Simply having it sitting outside on the side of the shop can work, but put yourself in the customers shoes for a minute: You go to pickup your vehicle, and are taken through the office to the 'pickup' area, which is a clean, well-lit space that gives the 'showcase' impression. It shows that you as a business owner care about your customers vehicles. This is just an idea.
Office Space - This is strictly a personal opinion, but my ideal space would be eye catching, but also minimalist. Consider if your business has a specific color-scheme (whether in general or in the logo, for example), and add some of this to the space. Simple wall-paint designs, clean sitting area with some commodities (coffee, etc), informational sheets at the front desk & waiting area, etc. Remember - this space may be the customers introduction to you and your business! First impressions are very important, and designing a space and maintaining it can have a lasting effect on your customer, as they will be able to sense your pride in the business you operate.
Although not setup-related, I would also ensure that you and your employees understand the environment and the need for cleanliness and professionalism. Cleaning floors often, keeping materials organized and put away immediately when finished with, etc., will help your shop maintain it's appearance and will allow your employees to really feel and grasp that they are not just monkeys in a shop - but part of a team of dedicated, professional detailers. Instilling that mentality is a major factor in any business, I find.
Hopefully this helps, and good luck! Keep us all updated with your progress.
