On my Hitachi 51F59 I have contrast at only 40% but to get rid of the picture looking too dark at this contrast level I have to crank brightness up to 66%.

Is this bad for the CRT's? With contrast at 40, anything less than about 60% brightness and the picture starts looking to dim or dark to me.

Contrast=White level, or how bright whites are, turn this up too far and the crts will wear out too fast and/or suffer burn in, and the fine detail in the picture will be lost. May also cause a yellowish tinge to whites.

Brightness=Black level, or how black dark parts of the picture are, doesn't affect overall picture brightness but turning it up does reveal detail in dark parts of the picture. Turning it up too far turns blacks grey and gives the picture a "washed out" look.

All sets differ but 66 does seem a bit high for brightness, maybe try a little light control in the room. As long as your blacks are still good at this level don't worry about it.