They may balk at, lets say, a figure skating event, but once you tell them you are throwing in food and allowing a get together, they will have fun. Make it theme-based depending on the sporting event occurring that week. Teens do not require as much hand-holding in terms of activities, most of the time they simply prefer to just be left alone hanging out with their peers.
Don't be surprised by a lot of eye rolling at the suggestion or even at the event, it is their nature, but they will want another tailgate party. Yes, they will still roll their eyes and maybe even proclaim how lame it is at the next one as well.