Well, the first question is, do you have insurance that will work overseas ("umbrella" or whatever)? (Your normal US car insurance by itself almost certainly does not work overseas.) If not, does your Cap One card cover insurance completely? (Many credit cards pretend to, until you read the fine print.) And is declining all CDW (a necessity for any possible credit card coverage) even possible in Netherlands (I know it can be difficult to impossible in some countries overseas, while not a problem in another country next door). I have no experience renting in Netherlands myself.

If you need insurance coverage, that's not covered by most coupons, etc. So that may change things completely (if one company has a lower rate before insurance, but another company has a lower rate including insurance).

The last thing you want is to be stuck with a giant bill because of some damage to the car. That would be so enormous (compared to the actual rental cost), it's to be avoided at all costs. That's why, if you've never rented overseas before, I feel you need to figure this out first (or just bite the bullet and decide you'll get all the coverage, since it's only a very short rental anyway).

Also, I hope you know how to drive stick. In Europe, even if you can get an automatic, it's typically about twice as expensive as a stick shift from most rental car companies (because they know mostly only foreigners such as Americans will ask for it!).