Smokey: Heavy Metal, often paired with weight-lifting to work off any built up stress.
Aurelia: Have to go with the stereotypical rich girl thing and say classical, but she's more likely to work off stress with a horse-back ride and the sounds of nature than anything else.
Toast: Jazz, bonus points if its a ballad with a soloist. He's the type of guy to find some way high-up place, lean back and just let the world pass him by.
Lucas: Good question, honestly. I don't know, he may just be the type of guy who just has to stew a bit while he works through his shit.
Clara: Same as above, to be honest. She's my least developed character right now.