Something I would appreciate in sieges would be if we could order construction of siege fortifications to circumvallate a city, and the digging of trenches to approach the fortification safely. Since the outline of cities in TW games always seem to have been from a limited number of templates it shouldn't be that hard to implement since it's just a matter of creating a slightly edited map with said trenches and/ or siege walls. And I have heard that one can order construction of ad hoc field fortifications on any battle map.