If you find yourself in a situation similar to this, there is a quick way to level the vertices. The approach is to scale to 0, along the axis that is perpendicular to the plane of alignment. So in this case, I want to scale the two vertices to be level along the z-axis.
The command sequence to do this is to select the two vertices, scale [s], the lock to the z-axis [z], then type  to zero the scale. This will align the to verts to the center/pivot point of the two.