Having guests in the company was always an excuse to do fun stuff. Like driving one weekend to a beach/volcano in one country, planning to go to the movies in another one, and lots of tasty food. We could expense the food so we only paid for a bit of extra gas or extra bus tickets with our pocket.
As a perk we have full kitchens in our offices, and a couple of times a week we cooked lunch together with the foodie/cook ones. It was usually tastier than buying food nearby. And it was fun to learn about each country's home cooking style.
I miss that and hanging out and sight seeing with coworkers on weekends or after work... The daily commute to the local office not so much.
I've just said this earlier in another comment, but I've never had what I'd consider true friendships come out from work acquaintances. I just don't consider "I have fun with you sometimes" to be friendship, and there's exactly 0 people from all the places I've worked at I would feel comfortable say, calling at 3am if I ever felt depressed. That's friendship in my eyes, and a company retreat would never bring that kind of intimacy that's for me a requirement to actual friendship.
Now there are definitely people I would work with again without hesitation, and I'd grab a drink any time with most of my old colleagues.
It helps that the most important aspect of our hiring process is about culture-fit - so much so that the final stage of the (pretty relaxed) hiring process is a presentation to everyone in the company who wishes to attend (regardless of role). Those presentations typically see 40% or more of the company attend. Crucially, every person in that presentation gets the opportunity to vote on whether the candidate is hired.
I've made friends for life at this company.