One day is not enough to see everything in Oklahoma City, but it is enough to understand why the city deserves more attention than many road-trippers give it. The trick is not trying to cross the entire metro area repeatedly.
Morning: choose one major story
Start with the Oklahoma City National Memorial and Museum if modern history is your priority. Alternatively, drive to the National Cowboy & Western Heritage Museum for the story of the American West. Both deserve enough time, so I would not rush through both before lunch.
Lunch and downtown
Head back towards central Oklahoma City for lunch, then walk through Myriad Botanical Gardens and towards Scissortail Park. This gives you a look at the newer downtown without filling every minute with ticketed attractions.
Afternoon: explore a neighbourhood
Choose one district rather than three. Automobile Alley works well if you want to remain central; Paseo or the Plaza District are better if you want galleries, murals and independent businesses. The Asian District is the obvious choice if food is driving the itinerary.
Evening: eat like you are in Oklahoma
Finish with steak, barbecue or Vietnamese food depending on what you skipped earlier. Bricktown is convenient for entertainment afterwards, while Midtown offers a more neighbourhood-oriented evening.
If you leave wanting another day for the First Americans Museum, Stockyards City or Route 66, the itinerary has done its job. Oklahoma City is much easier to appreciate when you stop treating it as somewhere to drive through.