Just my (2nd) 2 cents:
Something that comes up repeatedly here is "why don't all the shops locally get together and do a giant event?" From my business perspective, what would be the financial incentive to do so? Remember, while this is a hobby for the players, it is a means of income for at least two of the local shop owners (since Will's stated goal is to break even). There needs to be a reason for a shop to hold a tournament. That reason probably needs to be at least partly financial.
Only 1 shop in the area really has the resources to truly put together a 40+ person event, in terms of tables, terrain, etc. Brian may choose to elaborate on what goes into planning a tournament, but from speaking with Roy, Dennis, and about a dozen other TOs around the country, here's a rough idea of what it takes to run a large event:
1) Planning. Start 6 months out. Roy used to start the Hillbilly 9 months before it happened.
2) Dedicated staff. Most events of 40+ people have 5 or so volunteers, for rules & paint judging, pairings, etc. These people also build terrain, etc.
3) Money. Room deposits on that hotel have to be paid, usually upfront. I recall Roy talking about $2k deposits out of pocket for one venue.
4) Organization. Who paid what, where, etc. Are you selling t-shirts? Through whom? Is the design finished? Have you talked to the printer?
5) Advertisement. Word of mouth is great. NOVA did really well from blogs and word of mouth. It is by far the exception. Most events start small and grow.
6) Time. A TO is likely putting in 20 hours a week or so in terms of follow up. Terrain has to be built. Tables have to be made.
7) Details. Do you have dice/ tape measures/ rulebooks? Did you test scenarios? Does the room have A/C? Is there a curfew at the venue? Food? Drinks?
Thick skin. Be ready to deal with the bitching and still hype up next year.
After all of the above, what is your goal? To break even? I know of exactly 1 tournament, 1 year, that made money, and almost all of it was reinvested into terrain, tables, etc.
What is the ROI for a shop to do this? You need enough increased sales to justify the time and resource expenditure. Once you have one with a successful venture, what is his justification for allowing other venues to buy in. PLEASE NOTE: I am NOT suggesting Brian is against this. I honestly haven't talked to him at all about this, although from a gamer perspective I would be in favor of a single chief - makes decisions of whether or not to attend much easier. I just find it amusing when people post "the shops here should all get together and do XXX" - if you believe it that much, feel free to approach them and see if it can be set up.