The fair place to meet is Kansas City, MO — the city closest to the midpoint of Buffalo and Denver. From the farther side that’s about 17 hr 59 min of driving.
Recommended midpoint
Kansas City, MO
From Buffalo
17 hr 59 min
858 mi to Kansas City
From Denver
11 hr 41 min
557 mi to Kansas City
Denver has the shorter trip; the split is off by about 6 hr 18 min. The alternatives below can even it out. Buffalo and Denver are about 1,367 miles apart.
Buffalo and Denver are about 1,367 miles apart by road. Split the difference and you arrive near Kansas City, the city closest to the halfway point between them. That puts roughly 17 hr 59 min of driving on the Buffalo side and 11 hr 41 min on the Denver 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. Kansas City still makes a fair, central place for Buffalo and Denver to converge, splitting the travel instead of asking one side to cross the country.
If Kansas City doesn't have what you're after, Omaha and Chicago are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Buffalo and Denver.
Kansas City, abbreviated KC or KCMO, is the largest city in the U.S. state of Missouri by both population and area. It is located on the Missouri River at its confluence with the Kansas River, within Jackson, Clay, Platte and Cass counties. Read more →
Buffalo is a city in the U.S. state of New York. It lies in Western New York on the eastern shore of Lake Erie and at the head of the Niagara River on the Canada–United States border. Read more →
Denver is the capital and most populous city of the U.S. state of Colorado. Officially a consolidated city and county, it is located in the South Platte River valley on the western edge of the High Plains, and is just east of the Front Range of the Rocky… Read more →
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.
Estimates use straight-line distance and typical road speeds; real drive times vary with route and traffic.