The race that I would want to play are the orcs. So what I'm taking away from this is that in the open field the orcs can be quite deadly (and good at besieging castles), but when defending they aren't quite as effective. Couldn't the orcs sally out of their gatehouses to attack the siegers at the base of the walls? I mean you could while defending open up a gate, send some melee units through, close the gate. And use those guys to attack ladders or siege engines, and if they survive try to get them back through the gatehouse? I would try to aggressively defend as an orc in order to negate their defensive weaknesses.
Does any of that make sense to you guys or am I just insane?