An 800w redhead is way, way too harsh for that sort of thing. I would suggest having a couple of smaller units, such as 300w fresnels, which you can tuck away in the corners and use to give the speeches a bit of bling. Oh, and get a softbox and dimmer for your redhead.

The problem with large lights is that they tend to dominate the occasion and the punters get a bit miffed (understandably) when their "atmospheric" reception ends up with everyone walking around with scrunched up eyes and blinded.

This is probably the only occasion when you can get away with an on-camera light, something soft like a Photon-Beard Hyperlight, or with plenty of diffusion to really cut down the intensity. In this situation getting the atmosphere is very important which you're not going to do with an 800w flood. If in doubt, turn up the gain a bit and just use additional lights to give the subjects a touch of bling.