I adopted a new Siberian...

Outdoorschik - my husky can scale ANY chain link fence - no matter the height. She just uses her paws in the holes and climbs up and over. She has not tried to get out of my privacy fence though. I'm not sure which type you have.
 
When I was in college, I used a zip line. It worked ok for her but she did get bored and started to dig holes. So, I would not leave your girl out for too long tied up.
 
Good luck!

she is beautiful.... congrats!

jewliee - We have a wooden privacy fence, but there are struts inside at the bottom, mid and top that maybe could be used as rungs? It is six feet. She hasn't tried to climb it when I have been out there with them. She's doing wonderful in the crate all day, probably because she is used to being confined in a truck dog box for sled dogs. For the majority of the year, being crated, or confined only to the mud room that has nothing but kongs and kuranda dog beds and is heated or a/c will be fine. Maybe I'll just have to get a pet sitter to come in the days I want to be out longer than 8 hours. My other two hang out in the temp controlled mud and room and let themselves out the dog door when needed My concern with the zip line is that we have a small yard and it's tough to figure out where to put it so that she can't get over the fence and potentially hang herself.

What a beautiful girl! I've been thinking of getting a retired sled dog for scootering and such. Tojo's not big enough by himself, but he does love to run.

Would it be possible to make an overhang on the fence facing into the yard. so that if she does try to climb it, she'll just hit her head when she get to the top. Kind of like an upside down L?

I wouldn't want to leave her alone.  Zip line sounds like it would be dangerous.  Thing about the Siberian is that just because they don't do a certain behavior, does not mean that they won't sometime in the future.
 
My girl loves to dig under the gait.  She found out that it is the only area where there is not any reinforcement and she can dig through.  The brother just watches while she does all of the work!  I couldn't believe the first time I saw her half way out of the dog yard.  The only thing that stopped her was due to her rib cage being so deep, as many other dogs her size would be right on out the door with the size hole she dug. The gait areas now reinforced with cobble stone.
 
One thing that does keep them out of trouble is the amount of happy healthy play these two siblings share.  They have their toys, walks, but they love each other and play and rest together outside.
 
Siberians possess the ability to love just about everyone.  But I agree with you, the cats in your family do need to be protected from them.   I think that animals, not unlike children always should be monitored and not left alone to their own means. 
 
Your Sibe looks so much like my girl.  The only difference is the mask.  My girl has parallel black lines down her nose(as does her brother). 
 
Anyway, enjoy her!  She is lovely.
 

Would it be possible to make an overhang on the fence facing into the yard.

Here is a picture of an overhang:
[linkhttp://www.tracywerner.com/fencing.cfm]http://www.tracywerner.com/fencing.cfm[/link]