I have 10' ceilings in my garage.... errr, shop. I love it. I know
I'd be whacking the ceiling a ton if they were 9'. As well, if I were
building a dedicated shop I would do the framed floor as someone else
here suggested. Run all your DC and wiring below the floor. There are
so many advantages to this:

1. Unbelievably easier on your joints and back. My floor is concrete
and it's a killer. I have 25 of those 3'x3' rubber mats and my back
still gets very sore.
2. Your shop will be much cleaner looking and you won't have pipes to
bang material into. I know about this!
3. Your DC system will work much better. The piping won't have to run
from the floor to the ceiling and back down again. This is a big deal
in the DC world.

If you're set on a concrete floor with no subfloor then plumb your DC
and wiring right into the concrete. I've seen this done and it's
fantastic. You just don't get the benefit of the wood floor being
easier on your body. The only catch is you need to plan your shop and
tool placements very well. It will be a lot tougher to move your TS to
the other side of the shop afterwards.

Neil