Large Org Chart Best Practices?

I'm preparing to create a very large, company wide organizational chart (500+
people). I'll be using Excel for the data. To prepare myself, I've been
'practicing' by using a much small data sheet. So far, what looks like might
be the most challenging is the best way to show dual reporting relationships
- also printing out everything. If I do pages, that's okay. I'll just have to
stick them all together. :-)

Just looking for some tips and best practices that other Visio users might
have in creating a large scale org chart.

Thanks in advance!!