Yellowstone and Grand Teton are neighbors, joined by a short strip of protected land called the John D. Rockefeller, Jr. Memorial Parkway — named for the philanthropist who quietly bought up much of the valley that became Grand Teton National Park. From Old Faithful it's about 100 miles to the town of Jackson: past the geysers of West Thumb on Yellowstone Lake, out the South Entrance, down the parkway, and into the valley of Jackson Hole with the Teton Range filling the windshield.
It's a 2.5-hour drive, but wildlife jams and viewpoints stretch it — and the Tetons deserve two full days. Here's the route, the stops, and a three-day plan. Let Wanderply build your version and narrate each stop from geyser to glacier.