Had a nice experience in the Sixt counter. Stephanie helped me -- she is an employee who they moved from France to work in their new location. It also helped that I status matched from Hertz to Sixt platinum. Reserved a mid-size SUV, was offered my choice of Lincoln MKX or Volvo XC90. Try to find Stephanie -- someone else helped me when I sent back to exchange the car, and she wasn't as helpful (they also had fewer cars available at the time).
Was able to get the spouse added with no additional charge -- as a courtesy for Platinum status. Usually I was told they charge quite a bit per day.