its hard for me to enjoy drawing on a bus or train as i tend to find having people watch me is more uncomfortable and distracting rather than encouraging. it could be because I've had to deal with to many random old men trying to use it as a means to drum up conversation but that's just me.
but when its not some random spot in my house I've taken to the floor in corners of the library, certain spots in different parks either under a tree or if I'm lucky some huge rock or by the few decent waterside spots with a halfway decent place to sit and sketch
honestly i think you can draw just about anywhere it's just a matter of making it work