I hate to say it, but you will have a tournament for a select certain few if you do mate.
If you take a look at other realms, the pattern is the same. Healers are never allowed because they were designed to be next to impossible to kill 1v1 as the game was balanced around 2v2/3v3 arena.
Rogues, ferals and frost mages will be okay for the moment, but if you are to host a tournament like this weekly one of yours, then in the long run these classes will dominate more and more. Rogues with glaives, frost mages with spell haste and druids with 4k+ attack power etc.
In essence, it means that this tournament will be pointless to participate in unless you rock one of the classes/specs in my first post. Remember, many of us have already been playing TBC on other realms for a long time, so we know the outcome of pretty much every encounter. Now you are of course free to do whatever you wish, but if you intend for this tournament to be "a thing" then I suggest you ponder what I just wrote.
Anyhow, best of luck to you. :)