In advanced squad leader they had module called Red Barricades. It covered the battle of Stalingrad over many days. They had another for the Battle of the Bulge too. I always thought that was cool and would love to see something similiar in Sqb. I guess the issue is how to handle resupply, rest, etc.
Personally i'd love to see something like that that covers Operation Mercury - the air assault into Crete in ww2.