STP Visualization

[Brian Feeny]

Can anyone recommend a good tool for spanning tree visualization?  I  
am needing to get a good visual depiction of forwarding for many  
vlans, across 4 core switches.
Two of them are CatOS, 2 are IOS, root is different for many of the  
vlans, lots of port costing in place, in other words it would take a  
while by hand.

Thanks,

Brian