While BallyNeal and Dismal are far enough apart to be different weather and temps in Oct-Nov, I think on balance that fall is best for the region. The sticking point is that Dismal, SHGC, and Prairie Club close earlier than when the weather turns consistently too harsh. I'm not a weather expert on the region, but I think it is fair to say that around Mullen or Valentine, there may be 30-45 golfable days, with intermittent harsh weather after Oct 1. If Dismal, Prairie Club and SHGC close first week of Oct., many great to good golf days are missed, all due to the lack of availability of staff, if I may be so bold to offer a probable reason. But on the otherhand, who is going to come out there without a fair amount of confidence that a 5 day window of good weather in those Oct-Nov days will hold and allow you to play and enjoy... not to mention how college sports and pro f-ball begin to dominate people's weekends. For us golf fanatics, it may be worth the risk to seek those magical fall days, crisp, windy, and firm and fast. But, I'm not so sure it is an attractive economic reward for the clubs to maintain the costs to operate for the fewer fanatics that seek sand hill golf on a thrill factor basis.
Spring is hardy golf weather as well and attractive for the sort of hardy fans we have here on GCA. March can have a few great days out that way. But my preference is fall, after a frost or two at night, when the native starts to lay down a bit and allows more play from the otherwise too difficult lush native when it is warm.