Thanks Vyper - as Erny says you're more than welcome with whatever you've got. Plus there'll be plenty of Orcs and Goblins milling around that might need some extra direction!
I've been thinking about war engines too as it sounds like there'll be plenty of them on both sides. I like the idea of the morale effect from bombarding the city off table - perhaps a random table of psychological effects could be made up ranging from troops panicking and fleeing the walls, troops suffering from fear of their attackers, stupidity (shell shock!) and frenzy as they believe all is lost and vow to go down fighting. You could add into that reduced leadership, cool, WS as troops become demoralised and special events like a certain number of troops from each unit on the walls being called away to fight fire, towns people bolstering the ranks on the walls due to their desperation and so on...
As for working out who's affected - results could either be randomised, units could take a leadership check or (maybe a little complicated) each unit could have a card detailing the cumulative effects of the bombardment starting with things like reduced stat lines and working up to fear/panic/frenzy as they become more affected as the game goes on.
I haven't read the rules yet on what happens to troops in a section of wall that is hit but not destroyed by war engines - do they suffer any damage too? I would imagine that the bad guys' war engines would be set up and dug into earth works to target the city and so would not be able to target moving good units outside the city walls?
Don't forget the effects of biological warfare (firing rotting cows), firing severed heads and fire!
I'd imagine that, depending what the good guys bring, they could use their war machines as normal on the attacking horde?
I think madness lies in the direction of using points values! The rationing system sounds good. The Siege book recommends that the attackers should outnumber the defenders 2:1 - what about having some kind of unit cap for each side that would keep some kind of balance but allow reinforcements to be added as units are routed or destroyed?
I'm up in the Lakes at the mo and didn't get round to photographing my Orc and Goblin army. Here's a brief run down though.
Monsters
2 Wyverns with riders
2 Giants
Bound Manticore and Hippogriff
War Tortoise Ajax
6 x Trolls
Cavalry
18 Wolf riders
5 Wolf Riders
10 Gruntas
6 Snortas
Elites
20 x Ugezod's Mothercrushers (Black Orcs)
25 Big Uns
10 x Golgfag's Ogres
6 x Ogres
Infantry
30 x Ruglud's Armoured Orcs
25 x Orc Spears
25 x Savage Orcs
30 x Orc Warriors
25 x Orc Warriors
24 x Throgg's Despoiling Hobgoblins
2 x 15 Orc Archers
36 Goblin Sticka's
2 x 30 Goblin warriors (1 armed with spears)
20 x Swamp Goblins
13 Hobhounds + handlers
Artillery
Man Mangler
Skull Crusher
Lead Belcher
Monstrous Orc War Machine (3 man stone thrower)
3 x 3 man Stone Throwers
2 x Hobgoblin Rockets
Individual Characters
Army General, Army standard + 4 Big Un body guard
3 x Orc Shamans
1 x Goblin Shaman
1 x Goblin Shaman on Giant Spider
I'll get some pics up on Sunday when I get home just in case I've forgotten anything