Slate has put together a piece laying out how Democratic senators have been voting on cabinet nominations, and offering some analysis of why that might be. For instance, some nominations, while not ideal, are less troubling than others (ie., Nickki Haley for U.N.), and some fear repercussions when it comes election time in purple states in 2018 (ie., Sen Debbie Stabenow).
Here are the nominees that Sen. Debbie Stabenow (D) and Sen. Gary Peters (D) have said yes to:
Gen. James Mattis, Secretary of Defense: Peters and Stabenow
Nikki Haley, U.N. Ambassador: Peters and Stabenow
John Kelly, Homeland Security: Peters and Stabenow
U.S. Rep. Mike Pompeo, CIA Director: (neither)
Ben Carson, HUD Secretary: (neither)