Yup.... THISHoover dam. Bootleg canyon near Boulder city.
Also, I would skip the GC and head north to Utah - Zion & Bryce.
Zion and Bryce are amazing.
While you are in Vegas, I have a suggestion (if you like Thai food). Lotus of Siam!! Be adventurous though and don't order the Pad Thai. Look at their northern Thailand dishes. That's what they are known for and what you will NEVER find at any other thai place.