For a thrill ride better than any amusement park, try the one around l’Arc de Triomphe in Paris. I have read that no insurance company will insure any car that drives around it.
There is a little teeny roundabout near where I work, but most people avoid it like the plague (Midwestern US: “DON’T CONFUSE US WITH NEW IDEAS!”). I like it because there is so little traffic going that way it is an awesome short cut after work.
But to get to the point, the roundabouts I’ve seen in Europe that have traffic lights use the lights to regulate traffic going ON TO the roundabout, but not off of it. These tended to be very large roundabouts with a lot of traffic. It seems to work fairly well.