Want to get both the introverts and extroverts in the room to contribute thoughtful responses? Try taking a break from talking out ideas and switch to writing them down. The ideas you circulate will build on eachother.Everytime I have been involved in this activity I am amazed at the richness of the cumulative responses.
See this description, let me know if you have tried this and how it has gone. http://economictimes.indiatimes.com/Features/Corporate-Dossier/Try-brainwriting-if-bored-by-brainstorming-sessions/articleshow/4442442.cms