It would be nice if there was a Buffer option for surfaces. I often use model builder combined with a survey or a less detailed broader project environment with a more detailed close project environment and the connection edges are usually not pretty. (See screenshot)
If there was a buffer option where you could define the width of the area where the two surfaces are transitioned into each other, that would give a much nicer outcome. I think this same principle could be really useful in Civil3d as well when pasting surfaces together.