what i'd like to see regarding conquest is:
you get your province captured, you have three options: 1- flee, 2- burn the castle and stay in it, 3- burn whatever you can and run [this doesn't burn all castle improvements, but instead, burns a random number of improvements you've made in the province] to lessen the province's worth to your enemy.
another bunch of side notes i'd like to request are:
also, i also would like to see an option that have your vassals relocate, basically, all land owned by one family is that of the clan leader, he in turn distribute lands to reward vassals and as payment for their efforts and service.
another thing, spam us with events.
also, make it possible to have "visits" and talks to characters or even invite characters to a tea ceremony as methods of improving relations, having mere static modifiers is rather too plain for my taste.
also, regarding the ikko-ikki, i thing you should make them able to expand and plot, but also able to form alliances and whatnot