Adam,
To me, the benefits of ASGCA are mostly in playing great courses old and new that I would have trouble accessing otherwise. Playing those courses is a benefit which has furthered my design perceptions and abilities. In short, its a golf club atlas, but in person, and with guys/gals having opinions based on doing the work for real!
We also have formal seminars at the annual meetings on related design topics, that are not always sexy (i.e. permitting, insurance and business practices, etc.) but necessary. Its also about hanging with a great group of people, and learning informally from their comments in meetings, or in the bar!
Pete Dye, for instance, told me what per cent of slope on a green he considers pinnable (2.25%). My associate Eric Nelson was treated to playing with Pete at Prestwick, and got the whole story of exactly what ideas he brought back from there (Everyone was doing curves. When he saw the ditch on 18, he knew he could be different if he only did straight lines
..)
Tom Marzolf told me how they cut the cups at Augusta for the tournament,
Rees Jones answered questions about tournament set ups
Fazio shared tips on building a budget course (just kidding here)
Lots of older members, like Larry Packard, have told wonderful old stories, which give me a sense of how the profession evolved.
Damian Pascusso shared some ideas on the how tos of selling master plans to clubs, etc.
Brian Silva once shared his experience in working in solid rock, which came in helpful later, when I finally got a ledge rock job.
Almost any member can give me tremendous insight through an off hand comment while playing a great course. I remember Bruce Borland explaining some things about the Nicklaus bunker philosophy. Actually, I was able to ask Jack about his bunker philosophy and also some specific things about the whys and wherefores of designing Muirfield Village.
And of course, they all learn from me, too, although usually in the how not to do it category!
As a group, we have lobbied to exclude golf design from various state landscape architecture licensing arrangements, thus preserving the rights of a Pete Dye or Jack Nicklaus to practice the craft without formal training. We have assisted in setting up environmental conferences, and also meet regularly with the EPA on matters pertaining to permitting golf courses, etc.
Beyond that, members do get some job leads, standard contracts, media exposure, etc. as part of their benefits.
But mostly, I consider the best benefit is playing the courses we play, and associating with the best architects in the world to discuss things of mutual interest.