Summary: Many conferences and workshops provide forms to ask participants for feedback. It is important to participate in this process, and a great opportunity to provide input relating to issues such as speaker balance, childcare, and student/postdoc involvement.
Many conferences and workshops provide forms to ask participants for feedback. It's important to take advantage of these regardless of how you are feeling about the conference. If a conference was great and you wouldn't change anything, filling out a survey and saying so is a good way to encourage the organizers (and often useful, or required, if someone has provided funding for the conference). If the conference was not so great, the surveys provide a way to provide constructive feedback and suggestions.
Of course, it is useful to comment on perennial, practical issues of whether the space was adequate, the topics appropriate, the quality of the talks, etc. These are frequently included directly on the survey. But, there are also usually chances to make other comments, which can be a great way of bringing issues to the attention of the conference leadership. Here are some other areas on which you may want to comment that can be easy to overlook, but can make a big difference on how a meeting (or society) functions:
Gender balance of conference speakers. There are many resources about the problems of unconscious bias and how this makes it more difficult for women in many areas, including science. One straightforward way to combat unconscious bias is to make sure that the people up on stage giving talks - that is, endorsed by the organizers as being outstanding in their field - demonstrate that men are no more likely to succeed than women. If more than 50% of the speakers are men, it is worth addressing explicitly in your comments. (Of course, if the gender balance is good, it is very helpful to mention this, too!) A number of societies that have been intentional about speaker gender balance have also been successful at improving it, and drawing attention to the problem is an important first step.
Gender balance of awards. Many conferences have merit or travel awards, including awards based on abstracts, "young investigator" awards, "lifetime achievement awards", and so on. As with the speakers, it's worth noting whether a majority of awardees have been men. Some societies have two awards (one for a man, one for a woman).
Other opportunities for diversity. I've focused on gender balance as a start, but of course you might also consider geographical, racial, topical, career stage, or other types of diversity you'd like to see at a conference.
Childcare. Providing childcare makes an enormous difference in making conferences accessible for parents of young children. Because women are more frequently primary caregivers, they are typically more impacted by this than men (though, of course, it's nice to point out that men can bring children to conferences, too!).
Student/postdoc involvement. Does your conference have a student/postdoc association? A student/postdoc social? Career development aspects? Informally I hear a lot of students and postdocs say they like these events and want more. However, we have not typically heard this (as far as I know) at the society level. If we were to hear a lot of students and postdocs ask about it, it would help us to start something.
From my (limited) experience serving on a society board, members' opinions are highly valued and can often encourage the board to make changes (or, to keep changes that are improvements). As always, there are limited resources of time and money. Hearing from a large number of attendees about an issue may be more effective than hearing from one or two board members.
So, next time you are offered a chance to provide an evaluation of a workshop or conference you've attended, take an extra couple of minutes to provide some extra constructive feedback, and encourage your colleagues to do the same!