The seminal text in the field of play studies is Homo Ludens by Johan Huizinga. Huizinga defines play as follows...

"Summing up the formal characteristic of play, we might call it a free activity standing quite consciously outside 'ordinary' life as being 'not serious' but at the same time absorbing the player intensely and utterly. It is an activity connected with no material interest, and no profit can be gained by it. It proceeds within its own proper boundaries of time and space according to fixed rules and in an orderly manner. It promotes the formation of social groupings that tend to surround themselves with secrecy and to stress the difference from the common world by disguise or other means."

Something a bit different

The use of Thermography would be amazing to use for the utility chair. When the chair is not in use, it is an eggshell white, yet when it is in use the heat from the body causes a pattern to emerge of the heat that is created. This would be wonderfully playful, and incredibly different.

Retro space hopper

One of the most icon 'playful' toys are the Retro space hoppers. Since the 1960's this toy has been loved around the world for decades and created fun for adults as well as children. The shape and the design n the front are instantly recognisable. So linking with the re-design of the utility chair, the 'bounce' could be incorporated. Instead of the harsh look and feel of the chair a more cushion and bouncy feel could be used. Thus giving a more 'playful' feel to a boring chair.

slinky

One of the most famous child toys is the slinky. For years children and adults have enjoyed playing with them, so looking into the toy seems to be a good idea, as it fits the theme of 'play'.

different type of idea

This music video takes a blank canvas with the artist in front and paints it to a quirky, fun and playful way. With the mismatch shapes and the shades of cool nudes with a deep green work well.

http://www.youtube.com/watch?v=M5M8IDOhwK0&feature=related