You can do tabletop exercises, functional exercises, drills and full-scale exercises back in your own home community. However, I think it is hard to beat taking a large group of your stakeholders back to the Federal Emergency Management Agency Emergency Management Institute (EMI) training center in Maryland.
See this one story from the popular media of just one such experience by Racine County, Wisc. Getting the bosses to EMI is a big win!
Not specifically mentioned in the article is the fact that you travel as a group; you have your meals together; after the day is done, there is time to socialize with one another. All of these things help individuals to get to know each other. It has now been many years ago, but I ran the ping pong table until someone showed up who had a ping pong table in their home — then and only then, I went down in defeat, rather quickly. And then there was some dancing. As one person said, "What happens at EMI, stays at EMI."
The only downside to committing to this experience is that they have ice cream at every meal and lots of other desserts. Expect to gain a pound or two eating in their dining facility. I literally did see a guy put half a pound of bacon or more on his plate. Actually it was a separate "bacon only" plate. Yes, he was a big guy!!