Guests forgive a lot. They forgive a plain room and a late start. They do not forgive not being able to hear.
Audio is the least visible line item on a budget and the fastest way to lose a room. People will sit in a plain ballroom under flat light and stay engaged for two hours if the sound is clean. Put them in a beautiful room where the panel is muddy and they are on their phones inside four minutes.
The most common mistake I see is designing coverage for the room instead of for the seats. A room diagram tells you where the walls are. A seating chart tells you where the ears are. I walk the far corners during soundcheck and sit in the worst seat in the house, because that seat is where someone's CEO will end up.
For panels, lavs beat handhelds nearly every time — not for fidelity but for behavior. Handhelds drift away from mouths the moment a speaker gets animated. For fireside chats with two people, I still run a spare handheld on the table as a lifeline, muted until it is needed.
Podcast and content capture belong in the audio plan from day one, not bolted on the week of. If you are recording for reuse, you need an isolated feed, not a room mic pointed at a speaker array. The difference between a usable episode and unusable footage is one cable decided six weeks earlier.
And always record everything. Storage is cheap. A keynote that turns out to be quotable is not something you can go back and re-capture.