AAACK! The kittens are raiding the Christmas tree!

We put up our tree yesterday, and the 5 mo. old kittens didn't seem too interested in it. But today they are wildly climbing up the trunk, out the branches and batting at the decorations! It was quite a sight, both of them sticking out their heads with black eyes, and going for it! As soon as I got them out of there, they were back up again, going nuts! The kids were yelling and soooo concerned, and dh watched it in disbelief, and I got out the camera, and couldn't help but to laugh! The rest of the family didn't laugh at all...

I'm not sure what to do about it... There is the option of keeping them in the basement until after Chirstmas (it's a nice, finished basement that they are used to; they stay there at night), taking the tree down again, or pick off the most special decorations and let them go for it...Which my dh doesn't agree on, he doesn't think that's a solution. And the kids don't like that idea, they want to look at the pretty decorations.
Is there a 4th option? Is there a way to keep them out? I know that one of them doesn't learn from being sprayed... Dh says that the tree is one big cat toy... They're loving it! Quite a cat tree!!!

What about if we get a real tree, a prickly one? Usually we get a real one, but this year we happened to just pull out our artificial one, and it's not prickly at all. Would it help?

if you check the search function, there are a lot of threads on this. I know one suggestion is to put citrus smells on and around the tree (like orange peels around the base of the tree)

I'll try that. But how about a real tree? Will the pricklyness of a real tree prevent them from climbing it? I'm not so concerned about them batting at the decor at the bottom of the tree, but I really don't want them climbing it...