Any of the major 4 jap makers 125 cc cruisers have a low enough seat height, as do the 250cc cruisers...
The Virago made by Yamaha is 535 cc again a cruiser and again low seat height.
The 883 by HD is higher though well planted and a lower Cof G But not an easy bike to learn on and to me should really be discounted, but you might like them.
Kawasaki ER-6n ER-6F ( known in USA as the 650 ninja) can be lowered by both cutting the seat and shortening the shocker, this makes the sports tourer suitable for the vertically challenged
BMW though the seat can be reduced they cannot be shortened enough for someone of your stature.
Ducati Monster 620 M6 and the 695 can also be reduced in height and are designed to accomodate those of short stature including arms, not all italians are 6 footers hehe
Scooters cannot be reduced in height and the width of the floor boards make riding one if you are vertically challenged difficult,
however, the MP3 made by piaggio is practically self ballancing and so you step on and off, rather than having to put your feet down, this would be ideal for your stature and probably the best consideration.
Hope this helps