Just received my renewal from Chubb.
For a 10MM umbrella policy which covers 4 homes and 5 vehicles (one a collector car) and a small boat I pay $2,248.00. I receive a $300.00 credit for having $500,000.00 underlying coverage on the vehicles. Also have a pilots license but do not own a plane.
If you have a high net worth, I am not of the opinion that you need to have the umbrella limits cover all of your assets. However, the incremental cost of increasing the umbrella is relatively small.
Just my opinion, but if your budget allows and your assets are below 5MM, I would have the umbrella approach that amount. I have a familiarity with jury awards (because of my profession) and if you live in an area with high earning individuals, a serious injury caused by an accident close to home (where most occur) could exceed 2-3MM. Such a recovery is less likely for example if you live in an area with a high concentration of seniors, but anything can happen.
I also have a 19 and 23 year old on my auto policy and the above helps me sleep. As an aside, I also have been light on other aspects of insurance and only have coverage for larger risk exposures. By way of example never had a disability policy, keep a $25,000 deductible on my homeowners policies and only bought term life insurance when I was younger. But, again in my opinion, the cost of an umbrella policy is small compared to the risk. So I respectfully disagree with Dave Ramsey. I see no reason to put my assets at risk (i.e. self-insure) when the cost of insurance is relatively small. I would be willing to bet Dave Ramsey has an umbrella policy.