I am someone with a mobility disability and a genetic syndrome, and on days when I have my cane with me, I love to use the handicapped stalls, just so that I can have the grab bars to hang onto for stability. For the days that I have my manual/power wheelchairs with me, some of the big handicapped stalls, make it easy for me to have room for the wheelchair, and for me to still be able to move around in it. Both of my wheelchairs are 18" wide in the seat depth, but my power chair has a bigger, wider wheelbase than my manual wheelchair does. So, trying to get around it, when I'm in a handicapped stall, can be a little tricky.
I've been in some where I've had to leave my wheelchair outside of the stall door, with my mom, my fiance', or care support person, because the stall was apparently designed to be used by someone that used a walker. Not a wheelchair that was 18" wide. And, that was usually the only handicapped stall that was there, in the womens' restroom.
As far as others' reactions to me using it when I had my cane, I haven't had any problems when encountering women in wheelchairs, that were waiting for the handicapped stall. They'd look at me, and smile as if they understood. (Thank goodness for my syndrome being so "visible".) I always told them that I was a wheelchair user myself, so I know how it is when you have to go.
Samantha