Well at least Delta made it possible to book difference cabins on round award travel trips;

Starting July 21, 2016, SkyMiles Members will enjoy more flexibility when booking Award Travel, so you have even more opportunities than ever to enjoy new places and experiences. So what is the change? You will now have the option to book different cabins on the outbound and return flights of the same round-trip ticket. This means you can relax in Delta Comfort+™ on your way to your destination and enjoy our premium Delta One™ cabin to return home refreshed and rested.