The last reunion my class had was for our 35th, they tend to have them every 5 years. That year it was all kind of informal, but all weekend long. The only part I attended, at a park about 10 miles from my house, was a catered meal in the shelter house. It was fun seeing everyone who was there.
This has nothing to do with the original question, but I have to share something funny that happened:
We always get a book abut the classmates, usually info provided by a form that we filled out a few months earlier. It listed one guy as being deceased, and well, that's kind of sad. But then another guy spoke up, "Hey, he's not dead, I just talked to him last week! So we're all sitting around and he said, "I'm just going to call him right now" He lives in Arizona or CA or somewhere out west, and we all had to change our books, he was alive! They even passed the phone around to a lot of people who wanted to say Hi.
That will certainly be the highlight of that reunion