Houston and Omaha are about 795 miles apart by road. Split the difference and you arrive near Oklahoma City, the city closest to the halfway point between them. That splits the trip almost evenly — about 8 hr 40 min from Houston and 8 hr 35 min from Omaha.
That's a half-day drive from each side, so Oklahoma City suits an overnight or a weekend rather than a quick coffee — long enough to want a reason to stay, short enough to drive.
If Oklahoma City doesn't have what you're after, Dallas and Kansas City are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Houston and Omaha.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.