On 10 Feb you can fly with DL via DTW (as stated above).
If you take the first leg with KE, you can go to LAX, ATL or JFK and take a direct DL flight to LAS from there.

For the return flight on 15 Feb, the "pure DL" option does not exist because DL flies from DTW to ICN only on Mon, Wed, Fri, Sat.

Two remarks, martin_d:

1. You youself could have found this out easily by using the Skyteam timetable, which can be found on the Skyteam website. Just download it.

2. How can you expect anybody to give you advice here if you do not even mention the particular Frequent Flyer Programme that you would like to use? Without this information, close to nothing can be said about award availability.