I do a lot of aligns for moving parts around, but often I want to align a group of objects using something on the middle, such as making the inside of the washers level with a surface.
Currently, what I resort to doing is attaching a curve to part of the object by grouping, and I use the move command to move the objects, but then I usually need to align them in the other planes.
It would be handy to have a FromPoint option. When you choose an alignment mode (HorizCenter) and the FromPoint option is on, Rhino would first ask what (vertical) reference point you would want to align. You could snap to the inside of the washer and then THAT would be what you aligning.
Alignment type ( Bottom Concentric HorizCenter Left Right Top VertCenter FromPoint=yes):
[BTW, I usually include a lot of points in my blocks just for alignment and translations.]