Death Valley is the easiest big national park to reach from Las Vegas and the one most people underestimate. It's about 120 miles from the Strip to Furnace Creek — west over the Spring Mountains to Pahrump, through Death Valley Junction, and down CA-190 into a basin that bottoms out 282 feet below sea level at Badwater. The park is enormous (the largest national park outside Alaska), so a day trip only scratches the eastern edge.
Two days lets you do it properly as a loop: in via Pahrump with sunset from Dante's View, a morning on the valley floor, the dunes at Stovepipe Wells, and out through Beatty past the ghost town of Rhyolite. Heat is the thing that decides everything here — read the FAQ before you go in summer. When you're ready, let Wanderply build your version and narrate every stop, so the long empty miles come with the story of the borax miners and the forty-niners who named this place.