*sigh* I've spent 2 years of my life at this
point helping a restauranteur follow his passion of doing dinner theater. Needless to say, its been an adventure.
Not knowing dimensions of the room, of course, this is all just suggestions:
Cheep Solution: 4 fixtures (ideally
ERS, I convinced my group to do Source4 Jrs, you can get some really hideous
spill on the ceiling with PARs or fresnels), 2 trees one on each side of the
stage, at something resembling 45˚ out or so, to try and find that beautiful balance between side
face light and some sort of side light to get definition on people. The problem with this is the shadows on the set can be horrible. Buy the tallest trees you can find, you'll want to get the fixtures as high as possible (which, depending on the
ballroom, may not be that high.
Dimming: those shoe box dimmers work great. I'd suggest trying to put a
dimmer on a tree, since you increase your odds of getting different circuits on different sides of the
ballroom. Make sure your not going to have issues with
power, of course. (I
play the game of making them show me their panels, then start flipping breakers and figure out what is where, usually no one cares, but I do it anyway).
Control: if you get those NSI dimming/control systems, their usually great. I assume you'll be running it, so a single scene or 2 scene
preset console is usually enough. If your training someone else to run your show, NSI has some nice single scene consoles with
preset looks that you can program in. But that might be above and beyond what you need. Get a bunch of mic cable for your data and have fun.
Moderate Solution: Add some side light on another 2 trees. As I said, the shadows can be REALLY bad with just the frontlight solution, especially if the ceiling isn't that high and it ends up being fairly
flat lighting. REALLY BAD SHADOWS. (Just want to make sure that
point gets across.)
Expensive Solution: Depending on the show,
truss, top light, high side, really make it look nice. Buy a nicer
console.... and so on.
My shows I did on a budget, built to tour easily if they wanted to. Recently they acquired a small space so we wired a small
system in there, hiding things in the ceiling and really creating a
system.
Let me know if you need any other advice. As I said, I've been dealing with this group for the past 2 years, and designed several iterations of their
system.