Well, the biggest part is probably not the coding. It's most likely the modeling and animations. There is the question of balance, too, though.
Given my limited experience on this type of thing, the modeling and animations are somewhat more time consuming. At least if we don't factor balancing into it.
My new number 1 want is Offlinda Grey-mane as a marriage option. I swear she oozes more character than just about any woman in Whiterun. If not her, I'd settle for Karlotta. I'm sure Mikel the bard would like that.
