Tom and Wayne,
I've actually been watching this thread and trying to determine what course would be Maxwell's "signature" course. I think it depends on where in his career you are talking. But if I had to pick one it would be Southern Hills. It has all of his typical routing tricks. Core routing off of a hill, downhill opener, uphill finisher. It also has several of his typical hole design characteristics. Tight greenside bunkering, rolling greens and tilted fairways. If they would remove about 500 of the 4000 trees, it would be very close to what he would have imagined still today.
As for his patrons, Wayne is right. Flynn and Maxwell would have competed very little. Maxwell received two contracts in the Philly area early in the 20s. One with the Pennsylvania Railroad to build a course in Llarnech and one for the Melrose course where Mackenzie later was brought in as a consultant. Outside of that I don't think they would have even had the opportunity to compete. The only possibility was during the Depression when Maxwell was making yearly trips to Philly for renovation work at places like Pine Valley and Gulph Mills. I am wondering if he would have even got those jobs if Flynn was available. I know Flynn was already working on some project which is how Maxwell got the Philly CC job in the early 30s. If I were to guess, maybe for the Melrose job, but no other competition would have existed.
As for Maxwell's clients, a large chunk of his clients were in Oklahoma and were people who had made money in the oil business. Most of them were just investors and not the oil barons. But he did work for both of the Phillips brothers of Phillips Petroleum fame. Southern Hills and Hillcrest would have been those projects. The other prominent clients would have been people like Marvin Leonard at Colonial, the Reynolds family in North Carolina and Clifford Roberts at Augusta. Perhaps one connection between Maxwell and Flynn was Eugene Grace of Bethlemhem Steel fame. Maxwell and he were friends the last few years of Maxwell's life after he completed his work at Saucon Valley. Maxwell did have some notable people as friends though, but he usually kept friendships seperate from business, Grace being the exception and that was really after his work for him. People like Grantland Rice, JP Morgan, Lee Cruce (2nd Governor of Oklahoma), Wiley Post, Will Rogers, Bobby Jones were among his friends.
As for the assertion that he had some high-profile clients, I guess you could say that, but you have to remember that Maxwell's base of Operations was proliferated with oil money and those were the only people that were able to hire anyone to build golf courses. During the depression, it was only the extremely wealthy that were even thinking about luxuries like renovations to golf courses. But I wouldn't even compare the profile of his clients to that of Flynn, Macdonald or any of the other architects in the northeast or mid-atlantic regions. Talking apples and oranges with that.