I agree with HuckNorris. Need more info. Nevertheless, my two cents could get you started. I currently ski a 185 JJ in pow and all over. This one time I was on the hill without the JJ and grabbed anything I could from my buddies rental outfit. They were 170cm and were terrible in pow for me. Maybe it was simply not what I was used to, or maybe they were too short - it doesn't really matter, since my experience was not positive. I've started to err on the side of the go bigger motto lately with skis. True you might find yourself in some gnar with a long ski, but every other moment a loner ski will make your experience better IMHO.
You can get by with either size. You are about 175cm tall so the 178s will give you much for of a charger feel versus the more nimble and quicker turning of the 170s. In my opinion, if you are the open bowls, chutes and gnar charging kind of girl, first PM me, lets meet up in Jackson or MT, secondly, get the 178s! If you like to get silly in the tight trees and want something quicker edge to edge, then go the 170s! The rocker will def make them ski a tad shorter too.
I was in the same boat going between the 188 s7s and the 195 super 7s. For mach charging and straigt lines the bigger size was bomb, but for what the majority of my riding is, the shorter and more jibby/nimble 188 was perfect. Im 6'2'' and they are right at my eye brows. Couldn't be happier!
how stoked are you for this season in the village Japanada, only one more month!^^^^
anyways, same here with the JJ. Im 6'3 180, and i was told to go with the AK JJ (demoed both 195 AK and 185 JJ) by everyone,even the guys on blistergear... I already have 190+ chargers, and i really wanted a short jibby ski for tight trees and better overall control out of bounds. The 185s measure about 183, and theyre below my eyes, but i couldnt be happier with my decision. What im trying to say is Going short isnt that bad, what you lose in speed/stability, you gain in control and jibbtasticness.
As for chick-specific advice, My sister is 5'7 135 or so, and she skis 180s for squaw. theyre def a little long for her, but only 100 underfoot so she manages. Shes looking to buy 175 VJJs this season for a better match up, but she skis long skis because she rips harder than most dudes.