Saving and restoring the brightness setting of a display
One approach is to use the open source command line tool, brightness, to set the value on-demand. This way you could find your preferred brightness value and apply that value as needed, or per-profile.

Mac OS X Hints' discussion on Adjust brightness from Terminal covers the tool, how to compile it, and possible scripts to extend its use.

OS X Daily has also covered the tool in Adjust screen brightness from command line.