From above, in general, it looks like 15U WWBA is a bit on the early side and 17U WWBA is a "must do" event. Doing a search here, the 16U WWBA was described closer to the 15U...but that post was years ago, so I don't know how accurate it is to today's environment.
Can anyone speak more on the 16U WWBA? (i.e. What types and how many colleges tend to be at the 16U vs. the 17U? Is it more of a "must do" event for a certain level player but not for others?)