I know auto rental insurance is not usually a good deal if you purchase it at the car rental place at the time and different credit cards already include the coverage if you book the rental with the card.
I was made aware of the American Express Premium Car insurance available for AMEX cardholders and a few features make me think it might be worth the cost over their free coverage. First, it's considered primary coverage and you won’t have to file a claim with your insurance company first if anything happens. Also, the coverage amounts are higher and there is no deductible. It's $24.95 per vehicle rental (not a per day rate) up to 42 consecutive days. Coverage is worldwide except for Australia, Ireland, Israel, Italy, Jamaica, and New Zealand. We're trying it next trip and will see if the $24.95 is worth it.