We love these tournaments and the summer WWBA 17u is extremely heavily scouted. But, I don't have any familiarity with your other events, so I can't compare them.
Three points I would make:
1. As the 17u tourney field has been expanded, more and more games have been scheduled away from the East Cobb complex. It's a fact of life that with 4 fields in one place, and a 5th right across the street at Kell High School, you stand a better chance of getting seen if you're in that area than at one of the outlying fields. Unfortunately I don't know what you can do about that except go and take your chances.
2. WWBA events are absolutely the very best place for a pitcher to get noticed. For position players, much tougher, and if you happen to have a bad week with the stick you may end up wondering if you wasted your money. It helps if your team features pitchers who light up RADAR guns, because they will attract scouts to your games, giving the position players a chance to catch someone's eye as well. It's challenging for a position player/hitter, but if you're going to seek recruitment you'll have to face up to that challenge sometime, somewhere, and this is as good a place as there is over the summer.
3. The most effective use of a WWBA trip is to identify in advance which programs your son is most interested in, then have him keep them posted regularly via e-mail on who he's playing for, when and where. You might also ask those specific programs whether they will be more actively scouting the WWBA events or the events nearer to you. Also note that after July 1, the coaches can talk to your son face-to-face at the tourney, so this is a well timed event in terms of giving you the opportunity for valuable "face time".