I would be careful where I parked a Cayman overnight. There is a BMW factory in Greenville, SC and more than one person who did BMW's Performance Center Delivery (eg, picked their Z4 at the factory) have had their shiny new car keyed overnight.

So I would recommend park the car where it can be seen at night, particularly if you are staying at an inexpensive motel.

True anywhere in the country, I guess, but the internet images of those keyed BMW's is stuck in my head.