is there a way to make a layer automatically current with a specific command?  i.e. creating a viewport and having it automatically drawn in the viewport layer, or drawing a construction line and having it come in on its own layer

Yes, sort of!  The trick is to place your object via a Tool Palette.  Objects placed on tool palettes can have their properties assigned to include an insertion layer.  And even if that layer does not already exist in the drawing it will be created when you insert one of those objects.
 
I do this all the time with many different types of objects created from tool palettes.  Insertion doesn't make the layer "current" but it does place the object on the layer you've previously specified without need for further modifications.
 
Dave.heinsite2012-06-09 00:30:42

Sounds good.  I will try that asap!
Thanks!

I was able to create a new tool palette and set a layer to a command, but I was disappointed to find out that the command alias won't work the same way.

You can't use a command alias you would have to use a macro or lisp routine.