Don’t cheap out
As the employer, expect to spend some cash on the event. Don’t put all the responsibility for food and supplies on your staff, as though this were a family event and everyone needs to pitch in. While it’s fine to request that employees volunteer their resources, this is not a family event, and your employees aren’t your family. (Well, if you’re a family-owned business some employees might be family, but the point still stands.) This is a company-sponsored event, and the company ought to sponsor it.
Don’t make it mandatory
For whatever reason, some employees may not be able to attend, or they may not even want to attend. And while it may irk you that some would choose to refrain from the festivities, keep in mind that (a) mandatory attendance means you’re on the hook to pay regular hourly wages (for your non-exempt employees) and (b) if you treat people well, they’ll be happy to spend time with you.
Do celebrate during regular working hours
Unless this event is a lavish, all-expenses paid, you-definitely-wouldn’t-want-to-miss-this kind of thing, be considerate of your employees’ non-work obligations and don’t assume they either desire or are able to designate off-the-clock time with coworkers. If this is a work event, be prepared to allocate work time for it.
Do make it fun
Don’t forget the games! In fact, you may want to organize a volunteer “entertainment committee” for just this purpose.
And all of this brings me to …
Do provide resources
Planning a big party takes time, and it costs money. If your employees are doing most of the heavy lifting (in terms of planning, logistics, communications, etc.) provide plenty of both. Yes, they’re going to need a financial donation from you, and yes, they’re going to need to spend some work time making arrangements. If you think this event will provide benefits to your business (e.g., increased morale and team building), or you simply want to do something nice for your employees in exchange for all they do for you, don’t make them fight for every nickel, work inordinate amounts of overtime, or suffer through nasty looks from managers upset at how much time is being taken away from “work” to make this thing happen. Wholeheartedly support this endeavor, and make it known that you expect managers to do the same.