[MatthewS]

Selecting multiple canvases and changing properties seems like a natural improvement, but it doesn't exist.

just in case...

You can change text size on multiple objects in a single canvas using the fonts palette, and you can create a shortcut for it in preferences

You can resize multiple objects/type using master objects

Theoretically you can resize objects in multiple canvases, by changing the canvas size and choosing to print a single sheet per canvas. (that's how you do it in Visio, but I haven't had consistent results in OG)