Consider adding face alignment. 

• Click the face you want to align. 
• Then click the face you want to adhere to. 
• The first object would move to the second. 

This would: 

• Assist with alignment issues when you scale something that is not quite on grid. 
• It would rotate the faces to match allowing you to use local transformations

something like this would be *very* useful, maybe you wouldn't need to select the target surface either.

as you are moving a block about if a modifier key is held down, then a simple mouse ray selection can be used - snap the object to the plane defined by the surface the mouse is point at.

I used this a few years back on a project and it worked really nicely !

I just started playing with the new Vertex Snapping. What a quality of life improvement. Thanks!

how do you use Vertex Snapping, can't see anything in the app or doc site mentioning vertex snapping...?