I spoke to a relative last night abut my current story and while it appears the current concepts are a good start, she was willing to offer a little more.
One of the hurdles was that while planes are varied in their size and use, there is a question of what kind of plane to use (the alternative is I interpret it as "plane" in the sense this is a different dimension but that would only make planning more complicated as I have only upped the scale and would have to ask "how did the marionette end up in this plane of reality").
We hit upon the idea of perhaps a private jet, which would be more practical compared to my original thoughts of an airliner because I can create a more personal and customized space and I can worry less about filling the cabin with people who would question this living, jumping marionette running around. Simon liked the idea as well. I also discussed with him how the marionette could be on the plane because it is being transported to the home of the millionaire owner of the jet, who I figured could be wanted by a spoilt brat of a child in order to have a business jet fly many miles just to deliver a doll. There's also the oportunity to keep the action in the airline cabin, although Simon did put forward the suggestion that perhaps near the end the marionette, with balloon in hand, opens a door and gets pulled out by depressurisation to float gently to Earth and freedom.
It could also tie into the idea of oppression and a desire for freedom if the marionette's owner is s spoiled child, as it would give sympathy to the marionette (who might not want to spend its life with someone as bratty as her) either though empathy or by virtue of the child (who for now I might leave as a ghost character) being compeltely unlikeable.
The discussion reminded me of one clip shown on Charlie Brooker's Screenwipe some time ago around the TV show My super-sweet 16. One piece of footage had a girl throw a temper-tantrum at her mother after getting a Lexus of all things worth $67,000 as a birthday present. The girl threw a fit because she was shown the car the day before her birthday party when she wanted it given to her on the day. (Brooker, 2007). Even if this scenario was staged, it could serve as an inspiration for the behaviour of the millionaire's daughter and a source of motivation for the marionette.
Brooker, C., 2007; Charlie Brooker on My Sweet 16; Screenwipe; 1:27-1:50; available at http://youtu.be/0b7mwTK564o?t=1m27s (last accessed 9th Janary 2015)