If any pattern I would say that if a suitable piece of high ground is available on a golf course, that is where the clubhouse lies.
Thinking about LA area classics, Riviera, LACC, and Bel-Air all feature clubhouses on what is probably the high point on the club's property. *Maybe the 10th green at Bel-Air is a bit of a rise from the clubhouse.
Extending to the others I've played, courses like Olympic and Congressional follow this trend, and all of these furthermore make use of their clubhouse as a backdrop for the finishing hole.
I think that placing the clubhouse is critical for affecting the feel of a place - certainly there's a different "feeling" in the air looking up and seeing the behemoth at Congressional versus moseying up the 18th to the yellow manor at The Country Club...but not only because of the size/design, but because Congressional sits high above the course on a hill looking down on you, whereas TCC is tucked behind the 18th green waiting for you to come to it - it doesn't impose it's presence on you.
Of course, the prime example in my travels of a clubhouse imposing its presence on the golfer is Newport, where you are barely ever allowed to forget that high on the hill in the very center of the course lies the clubhouse, watching over your every move. Nowhere else have I encountered a clubhouse as imposing as this one, and I believe the placement of it there (and secondarily, the design) contributes to the general feel of the place strongly - it would not have the same effect if it were located at the beginning of the long driveway instead of the end.
Design-wise, many of these properties enjoy the luxury of having hilly or at least rolling terrain, as well as a section of land on the edge of the property that is both suitable for a clubhouse and not really ideal to design golf holes over. Certainly Riviera would be made awkward (to say the least) had Thomas attempted to build a hole where the clubhouse now sits. In the event that high ground exists, and is not otherwise wanted for golf, I believe that is the most commonly used location.
Maybe a good follow-up question is what is the best example in a top 100 classic layout where the clubhouse occupies land that should have instead been used for golf? Were any significant opportunities missed because the clubhouse was slated for the high ground? Perhaps Newport?