Reasons why Melee is on Sunday:
1 - Brawl is likely to be a larger crowd, as it is in *most* cases. It is also a slower game, so as a result it will require more time. Saturday is generally considered "more time".
So from a scheduling standpoint, you do your larger games on the day that has less restrictions.
Same for Halo vs MW2. We are likely to get 50% more Halo3 teams then MW2 teams, so Halo is Sat, MW2 is Sun.
2 - Someone asked about why not B/M on Sat and H/MW2 on Sunday. They are DIFFERENT platforms, that would require 2x the equipment at a minimum. Not likely we will get 40-60 TVs and Wiis and not at all possible to get 50+ TV and 360s.
So from an equipment standpoint, simply not possible.
ALSO see #1 above. Scheduling and the use of time is important.
Halo3 with 25+ teams running 4 games at a time until last 2 rounds when you have to go Full Screen, is a 10ish hr event. Sunday will not work for that, in addition to doing MW2 same day.
3 - Availability of Space
Simply not the sq ft available to do all of this in one day even if somehow we got enough equipment.
4 - As Hugo said, Melee players are Diva's and do not want to be around that other game, as if its some ex-gf or something.
So from an Event Management standpoint, is A LOT SMARTER to do them on different days.
Now, since my events run about 3hrs faster then virtually anyone else with like numbers, I would be willing to start Melee on Saturday and possible try to get 2v2's done so all we have is 1v1 on Sunday (which will likely go straight to bracket anyway unless we get 100++ people for Melee 1v1).
BUT BUT BUT BUT to do this, we need 20+ Brawl stations set up for Brawl on Saturday and 10++ Melee stations on Saturday. That means 30 set ups. Not one less.
On Sunday we will need 15 Melee stations minimum and we can knock this thing out FAST.