We have a system that seems to work for us where we place unbreakable ornaments on the bottom part of the tree (at kid-eye-level) and put the fragile ones up higher. We also have a "one-finger" rule, which always takes a few days of heavy enforcement.
After we finished decorating the tree and drinking our warm apple cider, Grandma, Grandpa, and Great-Grandma joined us for our first Sunday of Advent celebration, with candle-lighting, songs (kid songs and traditional carols), Bible reading, and more songs. It was amazing to have four generations of our family gathered to worship God and join in the anticipation of Christ's birth.
Flashback from December 2006