Don't know too much about the domains, but I'm getting the scimitar so hopefully this will help. All the stuff I know about the Scimitar is from reviews and the Rossignol rep in my region.
The Scimitar has a medium-stiff flex, and comes in a 181. For someone your size, that sounds like it would work fine. It has full rocker, whereas (as far as i know) the Domain has tip and tail rocker. The wider waist (99 mm) will be better for all mountain, and give you a bit more float in deeper snow than the domain. For park, they will be a bit harder to throw around, but that bit of extra length (as opposed to the 179 Domain) will give you a better platform for landings.
If you are really getting into park, and want something that will shred park more than the rest of the mountain, go with the Domain. You would have a slightly harder time in deep snow, but it might be worth it if you want a mostly park tool. The Scimitar will give you more all mountain, while still being able to hold its own in park.
I would go with the Scimitar.
