I definitely would not use the accessible stall if other ones were available, or if someone in line behind needed the accessible one.
To those of you in wheelchairs, or need the accessible stall for other reasons, do you wait in line, or do you head right to the stall? I usually look behind me to see if someone else needs the accessible stall, but it's an awkward situation when someone's disability is not an obvious one. I also ask if anyone in line needs the accessible stall before I go in.
My mom uses the accessible stall because she has a severe problem with both knees when she has to bend them too much (like all the way down onto a toilet) She needs the bars to get herself back up, or else I have to haul her up if she can't manage to grab hold of the toilet dispenser in a regular stall.

I'm a bit concerned that one day the dispenser will come off the wall, and she'll go flying back into the toilet...
****Quoted from post above:
Some people can choose to use the handicapped stall or Companion Restroom. For other people, there is no choice. I just wish that all the people who are choosing have looked at their options and chosen the one that inconveniences the fewest people.
End of quote***
Of course people who need the accessible stalls can use them - but are you trying to say that if someone else is in there, that it's not fair that the others have to wait to use the facility? What if they had to wait for another person who needed to use the accessible stall for the same reason?