And have that set at a height that requires a step stool to reach it. I would then also band it to the tv stand. However I obviously don't know the layout of where it will be located, so if there was the potential for someone to grab and run without being spotted, then this wouldn't be the safest method from theft. Otherwise it would avoid an easy grab.
What I feel is actually the most desirable solution is obtaining a display case similar to those used at stores like Bestbuy and Gamestop. Because the wii does not require you to actually touch the system to turn it on and off, there is no need to have easy access to it. If your planning on keeping pretty much the same game in all the time, then again access to the wii is not really an issue. Obviously the only issue is that it is close enough to maintain contact with the controllers. But if Nintendo isn't helpful nor any retailers in locating one of these for you, then obviously its not really an option.
One other idea I have is using an entertainment center shelf unit with a locking glass door. I looked on a few websites for an example, but wasn't too lucky. However I think some of these are still made. It would be visually appealing and access to the wii would be simplistic for staff. Also given the Wii's size, heat buildup wouldn't be an issue in a compartment meant to fill two layers of DVD units, receivers, etc...
