Interesting, we don't have anything like that here in UK that I know of.
You may be not looking in the right places. The beauty of the open-house home thing is that I was completely unaware of them as well.
The local periodical publications, galleries, and fairs that my customers and I look at are concerned with art and art. It's the same old crew, over and over again, and most of them are out of wall space.
The publications used to promote open-houses are concerned with real estate and home buying. The people who look at those things don't ordinarily hang out in the art market. One taps into a whole new market for which art is a new and appealing appealing novelty that intersects with their home centric interests. 1000 home improvement mavens will buy as much art as 20,000 art mavens.
To be more specific, the images I sell at those events are exclusively of local scenes photographed and presented in grandiose style. They validate the huge emotional and financial commitment a home buyer must make to a particular location. There's some psychology in play there, and it's the second part of the sales equation, right after simply finding an appropriate venue to reach such persons.
As we've seen in other posts on this thread, it's local subjects that sell best. Adding personal validation to that makes a powerful sales potion.
I should start a workshop and charge people for this kind of information.