Indianapolis and Los Angeles are about 1,806 miles apart by road. Split the difference and you arrive near Denver, the city closest to the halfway point between them. That puts roughly 20 hr 56 min of driving on the Indianapolis side and 17 hr 24 min on the Los Angeles side — the fairest single meeting point among the cities near the middle.
Over this distance most people will fly rather than drive the whole way. Denver still makes a fair, central place for Indianapolis and Los Angeles to converge, splitting the travel instead of asking one side to cross the country.
If Denver doesn't have what you're after, Albuquerque and Oklahoma City are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Indianapolis and Los Angeles.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.