With Sonar, you can achieve very complex routing arrangements. I think now is a good time to, at a glance, be able to see diagrammatically where the signal flow goes and what tracks, buses, auxiliary tracks have what effects, etc.
At the moment, say you have unintended reverb on your mix but you can't quickly see where it's coming from. Currently, you have to look through all of your tracks and buses, one by one, to see where it is. A routing diagram here would be handy. The ability to change routing from this diagram would be good too..... kind of like a node editor.
Also, a list of all effects and where they are used (which track, bus, aux track, etc) would be handy as well..... which the ability to selectively toggle effects from that list.