Work Trip in Denmark

I have a work trip to Sonderborg, Denmark coming up. My best flight options are to arrive in Hamburg, DE or Copenhagen and drive from there. Copenhagen looks to be around 4 hours and Hamburg is about 2 hours of driving time.

I will have to fly out of the same airport that I fly into and will probably stay an extra night in the city of my airport on the last day of my trip.

The driving difference is a consideration, but is there any issue with crossing the border from Germany to Denmark (and back) as a US citizen? Would spending an evening in one city or the other be more fun or more difficult having the car (just thinking about CPH and the little amount of driving actually done in the city). Is the drive from CPH to Sonderborg absolutely beautiful or worth a pit stop in Odense?