If we are talking about a tournament using single/double elimination system, I don't think it will have huge success, top players already had opportunity to play 2 tournaments recently(and lower level players can't pass the first 4 rounds).
On the other hand, I think it can be succesful if the tournament uses swiss system, because players below 1900 level will make a lot more effort to do their best perfomance in the tournament.
That said, I think it's also important to pick a decent map.Water maps are not the most popular ones, maps that can be very unfair(like salt march) the same, so be sure you pick a good map!
Last but not least, I don't think there is a custom map a good ammount of people think is fantastic, so don't think your tournament will be a good one just because of a map choice, you need good organizing as well.
Anyone can set a tournament up ... contact Taff if you want a subforum under General Tournaments once you've laid the groundwork (come up with viable rules and settings, map pack etc. and if you want to attract really good players, you'll need prize money)