Entries and other transition areas present an opportunity to use patterns in wood flooring. The distinctive appearance of end grain tiles with their circular grain pattern creates a strong impression in an entry. Designs such as herringbone, chevrons, or an English weave used in transition areas create interest and elegance.
The relative merits of using OSB or plywood for the subfloor under a wood floor has been a hot topic. The issue is the nail holding ability of the OSB especially if the moisture content of the subfloor has been high. Many experienced professionals prefer plywood subfloors. The consensus is that staples hold better than cleats if you are faced with a nail down installation over OSB. Here are two links where subfloor materials are discussed.