In Keeping Good Employees I talked about asking some simple questions. The biggest mistake I see managers make is to fail to deliver on what they say in such meetings.
There is the saying “It is better to be thought a fool than speak, and prove it.” Well it is better to be thought a pointy haired boss than to ask for feedback, then ignore it, and prove you are a PHB. This behavior is extremely common with a survey of employee satisfaction but can extend to any failure of management follow through. If you are not going to act on what good employees tell you – don’t ask.
If some of what they mention is something you disagree with, then explain that to them. Even bad decision making that is explained is better than no explanation and no action. If you end up explaining why no action can be taken on any suggestion then employees should rightfully (most likely) find you lacking. One aspect of the explanation is to educate them for future suggestions – there may well be factors they don’t think about that you must. But, even in such a case the best practice is normally to adjust the idea a bit to make it workable.