There is not much on the site to see now. Trees are grown up and it is difficult to follow a routing. From the pictures I have seen and the video Tom talks about, there wasn't anything that appeared to be of any architectural merit. They did have lofty goals for the Day Forest Estates development as evidence shows from the Traverse City Record Eagle, July 19, 1927:
"Located near the nation's center of poplulation, between Glen Lake, Leelanau County, one of the most beautiful inland lakes on the continent, according to many eminent authorities, and the senic Lake Michigan coast, in the vicinity of the Manitou Islands and historic Sleeping Bear Point, the far famed Day forests are undoubtedly the best site available today for the summer White House of the world's greatest nation. The superb water setting, the great natural forests, and the Riviera climate of Western Michigan, tempered by prevailing westely winds over Lake Michigan combine to make this site without a peer."
There was a special session of congress in 1928 to discuss a proposal to make the Day Forest Estates the permanent summer home of the US president. Obviously, nothing came of it.