Many companies hesitate to celebrate a 5-year anniversary 'really big'. That's reserved for round numbers like 10, 25 or 50, right? But no law says so. For your organisation, 5 years is a meaningful milestone. Almost always. That deserves a celebration to match.
The choice comes down to two things: who you want to invite, and which feel suits your culture. A grand party for 300 people is just as valid as an intimate dinner for the core team. It's not about the scale: it's about the intention and the execution.
Tip: use the anniversary as an external communications moment too. Five years is newsworthy for clients, partners and media.