im hosting a youth baseball tournament and would like it to be unforgetably fun ,still competitive.

Make sure you have enough facilities. Create some sort of tournament format. Try to promote the kids as much as possible. Have a Public Address announcer. Make MVP's for games/tournaments. Keep obnoxious coaches under wraps. They're kids not pros so the more annoying Bobby Knight type fathers that are there, the more problems that you will have.

dont make it bout just winning

Have a pyyjama match opening round. This where the kids come in there PJ's or similar clothes but still play seriously.