Lou,
Actually, I tried to make Ridgeview Ranch smaller in scale than Tangleridge, since they opened so close together. The greens and bunkers are both smaller. One reason is that the original superintendent was willing to hand rake smaller bunkers. On most public courses, the bunkers need at least 18 feet in each lobe to accept machine raking, so they get bigger.
Actually, most people on a course, or one under construction, are amazed at scale during construction, and how much it "pulls in" after time. I was called to another architects project (apparently they had little confidence in him) and spent a day convincing them that the bunker lines he had marked out weren't "too big" by measuring many of their existing bunkers.
As far as "pure" design, we consider scale in relation to the surroundings. Big greens don't look right to me in small wooded settings. Small greens dissapear in front of big mountains, or expansive sky. When we did Mission Dorado (me, as a part of Killian and Nugent at the time) we consciously made it a big course, because you could see forever.
The general rule is bigger courses for bigger spaces. There are exceptions, of course. We also try to mix large and small bunkers for visual illusion related to scale.
I'm not sure I consider scale and illusion to be the same topic. For the most part, its just something people sense, when a room is too big, a space too small, etc. Scale is trying to get human to relate to something a certain way. There have been lots of studies about the size of some successful public squares, for instance. Too big, and there is no feeling of enclosure. To small, and people don't feel comfortable, etc. As a city boy, I have felt a vague sense of discomfort while being in wide open spaces, like Sand Hills, but I think thats becuase I had never seen a storm actually roll in for miles (and hours) In the city, they just appear over the rooftops!
The best illusion I've seen is Fazio's Shadow Creek. On 11, a short four, he placed a huge bunker in front of the green, making it look much shorter. On 12, a series of bunkers get smaller and smaller, forcing perspective, and making the green look very far away. the green is smaller, and the flagstick is 6 instead of 8 feet, to complete the illusion.