I wonder if it would be a good idea to send all the people that attended the conference today a link to an online questionnaire so you are able to gather information either anonomously (some people may prefer to post what they didn't like this way) or with their name:
What went well?
What could have been done better?
What didn't you like?
How did you rate the venue?
Do you have any suggestions on how we could make the next conference better?
etc, etc, etc.
Only a thought.
We have a surveymonkey subscription if EduAdmins decide they want to do this.