A unique opportunity to combine two apartments on the sixth floor of one of Manhattan's most prestigious cooperatives - 88 Central Park West, at the corner of 69th Street. With 50-feet fronting Central Park, this grand 15-room apartment would offer a gracious layout accentuated by magnificent prewar architectural details.   The space has soaring ceilings, tall doorways, traditional moldings, and beautiful hardwood flooring throughout.  A private elevator landing  opens onto a 13-fooot gallery, providing an impressive introduction to the home.  A 34-foot entertaining expanse features oversized picture windows capturing a breath-taking expanse of Central Park.  The 19-foot formal dining room may be accessed off the gallery, as well as the living room.  The sprawling space would incorporate a windowed kitchen with a large breakfast room, library, family room, media room, and two studys.  There is a 31-foot master suite facing  the Park which has a large dressing room and large bath, as well as five additional bedrooms.  Built in 1909, this 12-story beige-brick apartment house with a three-story rusticated limestone base was designed by renowned architects Schwartz & Gross with French and Italian architectural influences.   This distinguished co-op offers residents the highest levels of service and privacy.  There is a full-time doorman/concierge and private storage facilities