In Spain, new licenses drivers are restricted to 250 cc the first two years. They are big sellers, and pretty convenient in big, jammed cities. I have one and I am very satisfied with it. Furthermore, bikes under 250cc are epempt to pay purchase taxes. Not surprisingly, since last year the biggest sellers are 125 cc, as car drivers with three years experience can drive them without specific bike licence.
Talking about bikes, I got my Tennessee motorcycle license riding a Harley V-Rod. I rented it for the day with my International driving license and went to the driving license station to get the licence. No restriction on capacity or power.
There was a time here when 400cc became popular, but they are not built new anymore. For just a little more weight people rather like -I would- a 500 cc or a 600 cc.
Talking about controls, Indian and H-D had the throttle on the foot if I'm not wrong. The reason? Police bodies asked to have the controls arranged in such a way that an agent could use his handgun while chasing a suspect.
Raul