Whether you add a crown detail or not depends more on the style of your kitchen. If it's a contemporary kitchen than clean lines are better, meaning no crown molding but just a simple trim piece. If you are doing a traditional kitchen than yes do the crown. It will add that extra detail that makes your kitchen go from average to nice. Think of it as an accessory just like you would a nice tie or jewelry with an outfit. What many people don't realize with good kitchen design it is all about the details to really make it pop. Don't skimp on them as they can really make the difference in the end result.