Well there is several things you need to consider.
Your probably going to finish the ceiling and insulate it. Most people flush mount lights to avoid
all the following.
But if this is the case and your going to put in down lights or even flush flourscents.
A down light need a IC rating that means that the light is self contained and can have any insulation lay on it. These IC lights are usually twice the price, Layin flourscents vary as to laying or blown
in insulation applied over them.
You can buy domes to insert over non IC lights and blow and lay insulation over your lights.
You have to understand this is a general building requirement to lights in insulated spaces.
IE gypsum board, light, dome, insulation. In no case will a non IC light be allowed
to be covered with blown or layed insulation. Blocking out or around the light is not Code compliant
because that space is not insulated.
Now your exact Code compliance might be a little difference, but it will be some of the things your going to run into if you want to down some lights, by Code.
You can use this site for light layouts
http://www.visual-3d.com/tools/interior/Default.aspx?id=14783
To understand the types of lights that you can choose from
Google.
Hardly a complete overview but I made comment to lighting in this
http://www.garagejournal.com/forum/showthread.php?p=4456620#post4456620 post.