Cross out the 168, if I were you I would try to decide between the 178 or 188,the 188 will feel a bit long at first but you will get used to it and it will provide great stability. The 178 will be good in the park since they will be easier to get around. So you decide and good luck!!
I'm 5'11 and 170 and ride the 188 last season for all mtn the size was perfect, but if I wanted them as a park ski I woul go 178. But I see them as more of a great jibby all mtn ski. I would get those in 188 then some thalls in 181 as my park skis.