Just returned from Chiang Mai, Thailand where I have done lots of riding over the past 10 years.
Until recently getting full size bikes was difficult unless you purchased them. However, if anyone is interested you can now rent full size Kawasaki and Honda motorcycles at very reasonable prices. Bikes that are manufactured in Thailand can be purchased without the huge import tariffs so they can be rented for around 40 dollars per day. You can just show up and rent them because it looked like many available. They do not even check for a license. I guess if you are stupid enough to rent a full size bike without knowing how to properly ride it is your problem.
I normally use my friends bike when I am there but because he was out of town (no keys) I rented a Kawasaki ER6 for the week. THE negative side of renting in Thailand is the lack of insurance... you damage it you pay or you do not leave Thailand-simple. A scooter is cheap but a full size bike will cost more to fix or god forbid to replace obviously.
I have never had a problem and IF you just watch how others ride it is very safe place to ride. Fantastic twisty roads thru the mountains etc. You must be use to lane sharing for traffic going your direction and opposite direction but it works very well and I honestly feel safer riding there than in Colorado since it is such a bike culture. Cars never pull out onto a road, everyone eases out so you have time to avoid. They may not look but since they ease out there is no excuse for hitting them. No sudden moves is the key.
PS, there is a fantastic hole in the wall MC gear shop with almost everything you need to ride from helmets, neck braces, and jackets - cheap. A little short of selection for MC pants and leg/hip protection but lots of everything else. Great guest houses are also available for cheap so the only expensive part is getting to Chinag Mai depending on where you are located. I work in Hong Kong so I go frequently anytime I get more than 3 days off in a row and I am not going back to Colorado.