My personal thoughts(aka ****ty opinions from a 4chan browser):
Definitely keep brawl if you want attendance high. While melee will probably get a higher overall, it will be because 90% of the brawlers will sign up for melee(who won't show up if brawl isn't there). The meleers will probably sign up for melee only(Because we suck ass at it. See: Me and kelly's team at 2fast =P). Try and start an event, whether brawl or melee, asap. If you can(again, opinions), try and open at 10~AM for signups, start an event at 12~PM. Anyone who wants to show up for that event should leave by 7AM if they have a 5hr drive(which probably won't be many people tbh).