I recently purcchased the 4', 6 bulb t-8 fixtures from Home Depot. They are roughly 8' from the floor level. My workspace is 14x20 and i used 4 fixtures. The lighting is fantastic and as bright as daylight!, it's nice to be able to see what I work on again.
I recently puchased the 6 bulb units from home depot, 4 of them, and hung them about 8' from the floor and my 14x20 garage is as bright as daylight with no shadows. I really enjoy being able to see what I'm working on.