Thanks for all the help.

I've come to the following conclusions based on all of my emails, calls and other research:

> My Thrifty rental car will come with liability insurance included
> My Amex card will provide CDW/LDW (damage to the vehicle)and will be the primary coverage since I have no other insurance outside of the US.
> I can take the rental car outside of Germany to Belgium and Holland so long as I disclose this at the time of rental and get a intermediate or smaller car (more expensive ones aren't allowed out of Germany)
> So my 170 Euro rate for a full week would be my cost, plus of course gas, parking, and maybe tolls. This would probably be more than the cost of train tickets and taxis for 2 people visiting 3 countries in a week, but not that much more.

So after all this, I am still trying to decide between the car and the train. I am leaning towards the car though...