Call them what you will....transitions, tie-ins, that seamless look, etc. The main thing though is that most of us know great examples of this concept when we see it.
In my travels, the greatest greensite with regards to these transitions, for me, has to be at the 17th hole at Royal Melbourne West. Any way your eyes move, be it L to R or R to L, everything about the rough/short grass/putting surface/surrounding vegetation/bunker continuity is damn near flawless. The continual flow from one part to the next is perfect!
What are some of your favorite examples?