Always stage rooms with a single purpose in mind.  Multi-functional rooms may confuse and intimidate homebuyers.  Identify  your home’s target market–these could be singles, professional couples without children, families, or down-sizers.  Then present each living space in manner that suits their needs while maintaining as wide an appeal as possible.  For rooms that, in your lifestyle, double or triple as a guest room/kids playroom/home office, pick the single use that best serves your buyers.