Owners of suburban office parks have begun to dedicate entire stand-alone buildings to amenities for tenants, almost like a clubhouse. At the Warren Corporate Center, owned by Rubenstein Partners LP and Vision Real Estate Partners, the venture is investing $12 million for a 19,000 SF building that will house a landscaped roof deck, full basketball court, fitness center, dining and meeting spaces, just a short walk from the five-building office complex.