When the tablet is docked to the entertainment system, it won't sleep.
 
If you power off the entertainment system, the tablet screen goes off, and there is no way that I know of to make it come back on again without powering the entertainment system.
 
Daydream does not seem to work either.  If  the tablet is docked, and the unit is on, Display --> Sleep is set to Never Sleep,  and is dimmed out, and cannot be changed.
 
I'd really like to have it Daydream with the clock, or some graphics, but it seems that it is either on or off.
 
I installed Daydream Launcher from Google Play, and that lets me manually initiate day dream.
 
I also enabled Developer Settings.  Never sleep when plugged in is not checked, and I cycled it on and off just to make sure.
 
But why can't it work like normal Android Day Dream?
 
(Latest Firmware installed OTA when I first used the device.)