fat skis in park aren't necessary (90underfoot isn't fat), and length is preference. now everywhere else this ratio does have a significance. i'm currently on a 179cm 100 underfoot ski and i def wouldn't mind a bit more girth just to keep me floating a little bit better, but i wouldn't be willing to go much longer since i'd loose a bit of the tight turns i'm able to make.
before i keep blabbing along, what's your point comparing these two???