Obviously all of the suggestions made are excellent, however could be costly. So making the the assumptions that this is a garage for detailing just your own cars, it's a 2 car garage and you don't have unlimited funds you'd want to keep the costs reasonable----so have the builder do the things that would be difficult or expensive to do later on.
To be able to comfortably open doors and walk around when two cars are in the garage you need at least 22' in width and if you want to have the back wall for cabinets and or shelves you need 24' in length.
You want a floor drain and hot and cold water and at least two 2 way electrical outlets on each side wall then a 4 way outlet centered on the back wall about 4' off the floor assuming this is where you'd put a work bench. Directly above this you could put a 2 way outlet in the ceiling so you can later hang a work light over the workbench. It's nice to have all of these on a separate breaker from other rooms in the house. If you have a 220-240V outlet placed 2 feet from the ceiling somewhere in the garage you can easily add an electric heater later that won't cost an arm and a leg to purchase or to run. Here's an example
Garage / Workshop Heater Dimplex DGWH4031 13648 BTU's Electric
All walls and ceiling need to be insulated and the garage door needs be one of those that have a foam core again for insulation so the garage will stay reasonably warm without heat and won't be rediculously expensive to heat. Would also be nice to have at least one souble hung style window in the garage that you can add a window air conditioner to later. I don't think it's a good idea to have your garage heating and cooling conected to the whole house units for safety reasons.
For lighting I find this to be enough (although some will say you need more)--centered over each bay a 2 way 4' fluorescent fixture positioned lengthwise -- these two on one switch so you don't have to turn on all the lights for general use. Then two more 2 way 4' fluorescent fixtures over each bay in line with the first two--so now you have a row of lights over the center of each bay. Finally 2 more 2 way 4' fluorescent fixtures at each end of the two rows mounted width wise. All of these controlled by another switch mounted near the first switch. This allows you to easily turn off all the lights at one position when checking your work with an LED or Halogen light. (Anymore I find myself doing correction and polishing with all the lights off and use just a couple of 100W LED spots to work under--the LEDs really highlight swirls and rids.) So basically you have a box of lights on the ceiling -- when working on a car pull it into the center of the garage under the box and you have lighting all around and plenty of room on all sides to move around. All of the fixtures should have 5000K bulbs as it seems to provide the most natural light--6500K bulbs are too blue for my liking. I find the inexpensive fixtures with no grills or covering to offer the most light and even coverage. Paint the walls white or light grey to help with light distribution.
Lights mounted low on the side wall are also a nice touch, but this impacts your space for those things we all need to hang in the garage so I just use a couple of 150w equivalent 5000K CFLs in clamp light fixtures that I bring out when detailing.
I have everything--cabinets, shelves, anything hanging on the side walls all at least 6" above the floor so I never have to worry about anything getting wet while washing cars and it makes it simple to hose down the entire floor when it needs it. I have my back wall covered with plain white kitchen cabinets from IKEA attached to the back wall but mounted on IKEA plastic legs that allow you to level them and keep them off the floor. This all can be done later DIY of course.
Another nice touch is a garage door opener with no center bar if you can find one---I have the iDrive Pro
Wayne Dalton idrive Openers This unit is mounted directly over the door on the front wall so there is no bar running down the middle of the garage ceiling.
A lift would be great, but very expensive and I certainly can't justify this cost for just detailing my own cars. If it was my lively hood it would be another matter.
All of this is going to cost you extra as most builders will not include this in a standard package, but it's not difficult or too expensive to have added electrical or insulation included while under construction.
Hope this at least gives you some food for thought.
