As mentioned above there is no one size fits all answer.

If you are getting a first/business class ticket for 100K miles, then I would say that it is worth using the miles. If you are getting a coach ticket then it depends.

Also if your dates are flexible, try to see if you can get a standard award in one direction at least. That will cost you fewer miles (or give you a better cabin). There are some dates in July for which standard awards are available (in either coach or business) for DTW-AMS.