All of the above. ;) It all depends on how much free time I have and how I'm feeling at the time. Usually during holidays I can sit down and build a rather complex story arc while I play... but otherwise I'll just go into short stories. Sometimes I'll plagiarise things left, right and centre, and other times I try to be more original. All depends on available free time and how I'm fleeing at the particular moment. :D
You can read a bit about some of the zany stories I've made while playing with my toys
here... just keep in mind that none of it is at all pre-planned/scripted/drafted or anything... I just grabbed some toys and started playing and the stories just fly out spontaneously. So I know they're not terribly good; but they were never intended to be. It's simply a by-product of what happens when I play with my toys. :D
Yeah, I'd still count that as playing, though not as fun or satisfying to me as creative fantasy play. But I often fiddle with toys cos really... it's just easy when you're short on time. Last night I had a fiddle with G1 Ironhide. No voices, sound effects, stories or anything... just... fiddled.