After I did the couple shots I tried several methods for the roaming shots.
I set up two strobes over the dance floor and used the 580 on camera for fill. It worked but I was moving so much and had such limited space to set the strobes that I was shooting into the strobes a lot. No big deal the effect isn't a killer. I was running back and forth turning on one light and turning off the other. Then I turned them down a low as I could using ISO 800, and still was getting too much light.
Shut them off and used the ambient lighting plus the 580 in manual, and then tried auto also. Manual was working much better for me because I could control the effect I wanted using the shutter and controlled flash output. Not only that but all of the subjects were at different distances. There was almost no way to to get the effects I wanted at a specific time using area lighting.
It wasn't that bad actually. I mean we now have at our disposal the LCD, Histogram, and our basic understanding of lighting all together with instant feedback. I wasn't even thinking about it after about 5 minutes. If I didn't get the look I was after, and understanding my equipment and light, I could get that look dialing the flash up or down, using a different shutter, or suing FEC and TTL flash.
the other thing that was annoying was that all of the walls have pictures hanging from them with glass over them. It was impossible to get pictures without seeing the flash in one of the pictures hanging on the walls. took some creativity before and post processing for sure.
Thee only area I think I did malfunction was setting up a back light/rim light/background light--a separator light, in short. I was using a black background (muslin) and I had no room at all. I was initially going to use an overhead gridded spot for the hair light for separation. then I thought better of it because people would be moving around too much. So I was going with a grid spot on the background. What I wanted to do was to create a gray oval in back of the couples. I couldn't get the light far enough from the background to get that effect. I moved it as close as it could and aimed it up skimming the backdrop.
I didn't like the effect, but there were so many people I didn't and would not have had the time to adjust it for every couple. If I had to do it again, I'd set up a small soft box overhead. So I screwed that up, but with some creative post processing the results are acceptable.
I'll post some results after I get the job done.
Thanks for all the help and suggestions.