A year has passed and the original problem I described has actually gotten worse relative to frequency. First, thank you to those who responded last year. I have systematically eliminated each potential source and now wonder if the problem exists in the laptop.
Once the keyboard connection drops out, the only way I have been able to restore it is to do a restart. The time span between drop outs has decreased over time to the point where I need to restart the laptop every morning when I start work. Once I do that, the connection is immediately restored and remains constant unless I close the laptop and do not open it for several hours. At that point, the keyboard may or may not be connected, but as mentioned, overnight it will always be disconnected.
This may or may not be related, but is something I have always wondered about. When attached to the power adaptor, my sleep settings are 1 hour for the computer and 15 minutes for the display. All option boxes are checked. When I reopen the laptop after a few hours away, I almost always see the dialog box stating the computer is scheduled to sleep in x minutes and giving me the choice to not let it sleep. It should have gone to sleep after an hour, so that mystifies me. After being closed overnight, I do not get that box when I open it. It picks up right where it was when I closed it.
Not to muddy the water, but another odd thing just started happening and I believe it concurred with the installation of Sierra 10.12.3 (the first install of Sierra). When I click Restart, shutdown occurs and then I get the start tone with the display backlight, but that is where it stops. A force quit and subsequent restart have the same result. I can get it to restart normally once I disconnect a powered hub I use for three external drives I use for extra storage and backups. That has never occurred before and I have had this set-up for quite some time.
Sorry for describing what may be problems apart from the bluetooth issue in the same post, but I am an advocate of full disclosure of my observations.