I'm a big fan of daisy chaining campaigns together with the "Request Campaign" action. This has allowed me to isolate the parts of our campaigns that happen over and over (like alerting the salesfolk to interesting activity) and call them up whenever I need them, versus recreating those actions over and over in individual campaigns.

I also like "Request Campaign" because it allows me to get a little fancier, logic-wise, that I could with just the Choice options for different flow actions. I'm looking at you, insanely intricate lead routing rules for demos that require me to set different options based on location AND company size!