love all these suggestions especially a CAB day or lunch ahead of time! I’d also suggest getting your sales and CS teams enablement materials to encourage them to take big accounts out for dinner or lunch after to deepen the engagement at the account level, and put your leadership team in those meetings/side events where it’s lucrative.
for video, a mix of “on the fly” and formal/well produced is good to consider (you’ll thank yourself for variety!)
if your budget allows for custom merch I love adding that in
if your event is a single track, making sure you have a session that’s interactive (a small group workshop or some equivalent) goes over really well to get them working and thinking together!