@Russ , I did a bit more playing with routines and follow up mode. You can't run another routine after one or activate a device after with out saying Alexa first, but you can run a routine after a device trigger.
If in a routine you add a say command asking "do you wish anything else?" then you can say "yes, Alexa, run....." or "no, Alexa, thank you" and she will respond to both. Doing this you could make it seem more like Alexa is interacting.