Having spent the last couple of weeks studying the large scale battles it is readily apparent that it is easier to represent these in a series of rolling tableaux unless one is lucky enough to have access to a huge table., I would strongly suggest not building dedicated battle boards but to go for free standing terrain that can be dressed up or down as the tableaux requires!!!.
The only time I see integrated battle boards being needed is where amphibious landings occurred or unless one wants to model the bombardments of forts!