I must say that after reading all the posts on here regarding cats and Christmas trees last year, I was very contemplative on putting a tree up this year. I didn't even bother last year because she was only 8 months old, but I figured I'd give it a go this year. And I'm glad I did. I am proud to say that after one week and 3 days, my little angel has yet to neither destroy the tree nor knock one ornament off. I made a point to not to hang any breakables at first, but now I've been able to add some.
The only "secrets" I used to deter her are as follows. When it was first erected, I didn't play with her around the tree. As cute as she looked trying to play chase around it, I just ignored her. Also, by promptly putting all my presents around the tree, she is not interested in working her way through the all the bags and boxes to climb up the tree (I know, I'm a freak, I already have all my shopping done and presents wrapped!). If you are not as anal retentive as I, you can just wrap empty boxes to put under the tree so it's not as enticing for your kitties to climb in, plus if they tear into the faked wrapped presents you won't be as upset!
Of course she always gets plenty of play time with the mommy and the daddy, plus she has her own tree to play on and plenty of her own toys.
I hear and read all the time about people's "bad" kitties and I know they are all different, but I sincerely believe if you take the time to ensure your kitty has plenty to distract them and play a game of chase every evening, you will reap the benefits. My hubby and I both work full time jobs, but we ensure to make the time and play with our baby when at home and it seems to be paying off.
Good luck everyone with your kitties and the Christmas trees. Keep in mind; I only have one cat, so I can't really give any useful advice for multi-cat households. Also, my tree is short, fake and rather full. I guess a little less tempting than the real ones. But when you have a pet, you sometimes have to make sacrifices to ensure your whole families happiness.