Tip for #21 (increasing noise)
1. Use multiple speakers in different locations. Single speakers tend to be turned louder, people then talk louder...
2. Breaks for toasts / games. If everyone has to listen, the talking noise level resets a bit.
3. No Alcohol. Yeah, this is a game changer. Some people even won't come if they know there is no alcohol and some will go early. The other ones have a better sense for noise.