Fab room ceiling height?

As mentioned, 8 feet is gonna feel really low once you start adding lights, etc. If it were my shop, I wouldn't necessarily be concerned with the height of my machines -- most floor standing vertical bandsaws are 6-7', unless you're getting a monster DoAll or something like that. My concern would be getting a gantry or hoist in there as @SIX225 said. I don't know what kind of fabrication you do, but if you're like me and work alone, something to lift and move your work will be necessary and 8' ceilings will drive you out of your mind.

Go as big as you can afford now and you'll thank yourself later.