Absolutely gorgeous place to visit if you want to step away from the crazy life on the Strip in Vegas. I would even dare to say it's even better than the strip! :)
It's about an hour or so away from the strip so a day trip is more than manageable. It's absolutely breathtaking just driving up to it and the closer you get, the better the view is. Be aware that there is a fee ($5) to get on to the National Park but I wouldn't really recommend this unless you're camping/going on a boat ride.
Further down the street is the famous Hoover Dam which absolutely took my breath away. It's absolutely gorgeous. There is parking but you have to pay $10. I HIGHLY recommend this place!