Well, back when the kids were little, we had the two-fold problem, of how both cats and kids would handle the tree. So, we put the tree into Mandy's playpen. It worked great. The kids stayed away from both the tree and the cats and the cats slept in the playpen under the tree.
We're planning on either not having a tree (not an option as far as I'm concerned) or just putting the wooden and plastic decorations on. We have some that are unbreakable and rather tasteful, in spite of our eccentric personalities. We don't have poisonous plants like holly and poinsettia in the house. We do put up mistletoe, but it is over the doors and the cats can't reach it.
I pulled QC out of the tree one year. I walked into the living room and found her at face height, hiding in the branches. I've also pulled Merlin out from under the tree which was quite a feat as he weighed a ton at the time. Berfert has been known to use the ornaments for batting practice, and last year all four of the older ones slept under the tree. I don't worry about it too much, or didn't until this year when we'll have six cats who'll be celebrating their first holiday season. Seven if we haven't found a home for Diana by then.
The nut bowl is in the most danger, the cats play nut hockey in both the kitchen and living room. Berfert even hauled one into the bathroom and tossed it into the tub so that he could bat it all over the bathtub at 3 am. I thought it was funny. Rob was a little upset as he had to work that day and couldn't sleep through the racket. I took the nut away and Berfert was crushed.
I doubt if I helped any with keeping the kittens from the tree, but I had fun remembering how our cats have gotten into the holiday mood over the years.