A recent article in Grassroots Fundraising Journal, "Let's Do a Fundraising Event (Or Not): Fundraising Event Criteria for Your Organization," looked to tackle just this topic and, as the title suggests, offers a key bit of advice: set criteria for events and do so when not in the midst of event planning. I agree with the author wholeheartedly and believe this sort of preparatory work can help prevent awkward moments later on. Who wants to crush the dream of an enthusiastic staff person, board member, or volunteer? It's certainly not at the top of my to-do list. Setting criteria before an event idea is even floated by one of those well-meaning people can prevent just such a moment (or worse: prevent an event from rolling ahead when no one is willing to be the one to say "no"), because if everyone has a list of criteria to refer to then they can start the evaluation process on their own. Even if they aren't able to review the list objectively it provides a way for anyone else involved in the conversation to make the evaluation process seem less personal, which will keep morale higher and new ideas flowing.
I think the criteria suggested in the article are all insightful and helpful; however, there's one criteria I would add: time spent on the event must be more worthwhile than tasks that will be missed while focusing on the event. What do I mean by this? It's important to not only factor staff time into an event budget, but to also consider what staff won't be doing while spending time orchestrating an event. Presumably there are activities staff will either not be able to do or will have to put off doing while in the midst of event planning and any event criteria should include some assessment of that trade off. Being honest about time management and acknowledging there are only so many hours in the day isn't a weakness, but a strength. Ignoring those realities can lead to decreased morale, hesitation to do future events that would actually be a great use of time, and volunteer and staff burnout.