unless you go for an older motorcycle, it's hard to find a more upright seating position, they are comfertable, and alow better visability for riding around in town.
I still have a 71 Honda CT90 (trail 90) with a dual range transmission. The engine design is similar to the Honda Cub 50. I can ride the little bike all day and not use a gallon of gas. I recall it's rated at something like 160 mpg at 25 mph. It's licensed for street use and I occationally ride it to work but mostly use it for putting around on trails.