I have the most experience with the U.S. elections.
This year we saw a lot of innovations around live-streaming debate. In New Jersey there was a governors' debate that we partnered with, and they had multiple media partners. They took questions from Twitter users both before and during the debate.
That's a best practice: allowing people to tweet before the live event, but also to tweet during it if something really encourages them to get involved. They took those questions live, and we also covered what people responded to at the end of the debate through Twitter data.