I've looked into the options to make your employees work better as a team and the best ones are listed below:
I also thinked on a weekend survival course. It will teach to your employees how to work together and will also teach them how to survive in a forest. The bad side is that some of your employees could not like forests.
You can also try a two-days diving course. It's very nice and many beautiful photos can be taked on the trip. One good point is the duration of the course, just two days. A drawback is that some of your employees maybe can't swimming.
I think the first option is the best, this is the one which can teach more useful things to your employees. And I'm shure that you can pay that.