Roundabouts come natural to me. If not, they could be stressful.

I think car rentals make the most sense to: a) visit places in the countryside, or b) to link major cities (though trains can do that too…), or c) both of the above. Driving in the “big city” is best avoided. It’s more stressful, the GPS is less effective (turns can come too quickly), parking is a hassle, and you generally can’t drive in the historic core anyway. So, we left the car at the hotel’s garage until it was time to move on.

Perfect places to drive are like southern Bavaria and the Black Forest in Germany or (I’d imagine) the Loire Valley in France. The hill towns of Italy would be great too, but I think the drivers become crazier the further south you go and car rentals are much more expensive in Italy than say Germany (I only paid about $600 for 10 days for an SUV… even with gas and parking, it was the cheapest way to get 4 people around by far).