Don't miss: At the dam, be sure to take a stroll along the sidewalk at the top for a great view and the chance to stand on the state border — with one foot in Nevada, the other in Arizona. Bring a picnic to the park, which has countless perfect scenic spots for lunch al fresco, many of them shaded (you can also grab a meal at the boat harbor).
What you should know: If hiking in the park, again, bring a lot of water: The National Park Service actually suggests two liters or more for long hikes. The air is dry, and temperatures can skyrocket.
3. Valley of Fire State Park
About an hour (55 miles) northeast of Vegas and a popular spot for camping, this park regularly wows day-trippers with how over-the-top stunning the colorful sandstone formations are.
What you can do there: See 3,000-year-old petroglyphs from the Ancient Pueblo peoples (Anasazi). There are some easily viewed right at the Atlatl Rock picnic area, and others that you can reach via a gravelly quarter-mile path. The park also has 18 miles of roads: The scenic White Domes Road will take you past Rainbow Vista, an oft-photographed panorama of undulating rock layers in reds, whites, browns and golds.
Don't miss: Pass the Rainbow Vista at the end of the road, and try an easy-to-moderate 2-mile-long loop hike to White Domes (a group of round, creamy sandstone mounds) that will allow you to get up close to the striations of rock. About 100 feet of the trail is an almost tunnel-like slot canyon, where you can see every vein of color in the walls surrounding you (and get some welcome shade).
Wildlife: You may spot roadrunners, ravens, snakes, coyotes, black-tailed jackrabbits and desert big horn sheep.
What you should know: There's no restaurant, just a few snacks sold in the visitor center gift shop, so bring your own. And you won't be seeing many gas stations, so fill up before you leave the city.
And consider timing your visit for early in the morning. It's often 15 or 20 degrees cooler at sunrise than at sunset and the fiery glow on the red rocks is just as beautiful.