Regarding the Memorial Day tournament you mentioned, I don't know anyone that's gone to that (from CA). At least in CA, HS teams are just finishing up and players are taking a breather and getting ready for JOs. Also, colleges are still playing so not sure how they'd be on the recruiting trail. I don't think it would hurt to miss this, IMO.
Regarding the 17U WWBA, this is a great tournament no doubt. But, that's a lot of eggs to put in one basket. What if the coaches you are interested in don't see your son play? What if he doesn't do anything to stand out? What if the game the coaches come to gets rained out? There's just so many things that have to go right to make this your only event. I think it should be on the list, but it shouldn't be the only thing on the list.