Two years ago, when I had a just 1-yr old son and a 3-yr old daughter, I found a bag of old 4-cup coffee maker filters (left over from college, I'm a pack rat), some red yarn, and bought a cylinder of snowman foamie stickers from one of the local craft stores. My daughter and I sat on the floor making cute kid-friendly snowman ornaments for the tree. We turned the filter so the narrow end was at the top, and it gave us plenty of room to create. Then, I threaded the red yarn through the top, making a loop to hang the ornaments. She LOVED the stickers, the quality time we spent together making them, and being allowed to decorate the tree herself. It was very nice not having to worry about any of the "good" ornaments beng broken. Plus, the tree looked so cute being kid-made, and having one type of decoration made it look very "Martha"...but not quite.
The "good" ornaments were placed on garland I had strung across our windows and mantel, waaay out of reach from andy curious hands. I did this when my dog and cat were young, too.
The cool thing about the coffee filter ornaments is that when it's time to take the tree down, you only have to keep a few of the ornaments, if you want to, and they store nice and flat! We have several on our tree this year from '06!
The hardest thing to do is putting down the urge to do "what's next" and just enjoy "what's now".