Beyond the visual map, i wish there was something like manors you could give away to children, family, courtiers, etc, that were sources of revenue. Of course you would want to keep the majority in your own hands, and they could generally be tied to counties or baronies, so there are 'x' number of manors in an area, not an amount that can be continually increased and scaled up. This would give something else to go to war for, or rather with would be like what often was at issue in private wars below the kingdom level, which is the land and its revenues. You might go to war with neighboring counties for a number of manors to increase your influence, power, etc, in that area with a somewhat silly 'fabricate claim to x' mechanic.