Three years ago, my son wanted to play Minecraft with other kids. I wanted him to play in a safe environment. I found The Sandlot, as well as some other whitelisted servers. I registered him on a half-dozen whitelisted servers.
He fell in love with Sandlot and its friendly players. His brother quickly decided that he wanted to join the fun. After a few weeks of watching my boys enjoy The Sandlot, I wanted to have fun too. I bought a PC Minecraft account, joined Sandlot, and have never looked back.
Sandlot has a nice mix of kids and adults. It is a welcoming server with many play options. The wholesome environment is pleasant compared to the vitriol present on other servers. I highly recommend this server for youth and adults.