Not an easy answer as some of these camps are nothing more than moneymakers where large numbers of kids are run through. At those camps, unless you throw 90+ or hit a ball 450 feet (in both cases they've probably know of the player anyway) there probably is very little benefit.
On the other hand, if you've done your research and the camp has somewhat limited numbers where more individual instruction occurs, it's probably a good idea "if you are targeting a specific school". The opportunity to perform in front of coaches of a school he wants to attend for a couple hours/day over a few days can certainly get your son a good look. From personal experiences I know of at least 2 young men who will be playing college baseball next year due to attending their "targeted" school's camp.
The benefit to showcases is that there are many more schools in attendance. The downside is if you are not streaking during those few games (10-15 AB's?) then your opportunities are more restricted.
Either way, do your research and play as much as possible in front college coaches/recruiters. If the player is good enough, the opportunity will present itself.
Good luck and enjoy every minute!