I agree.. being a "work from anywhere" company we have adopted an annual offsite as a key ingredient in establishing the culture we are looking to inculcate in the company.
We have folks in 5 different time zones and once a year the team meets for a week-long offsite. Agenda is managed and executed by an external agency. Includes work as usual + lunch & learns + collaborative dinner experiences.
In addition to our employees, key partners, consultants also participate.