At the time they were created in 1983, Crowne Plaza hotels were branded as "Holiday Inn Crowne Plaza". And they were just larger and somewhat slighty better than HIs.
It is now a brand on its own, which has largely evoluated (and evoluated to the best).
Most recent CPs are very good hotels for design and location: Copenhagen Towers, Milan city Centre, Changi airport, Dubai Festival City, Amsterdam City Centre, Istanbul Harbiye, Toulouse, etc. are great properties. But still some might be old and surely need some renovation (as Sheraton or Renaissance hotels might be sometime).