Sin City Yoga is owned by Angelica, who is the best yoga teacher I've found in two cities now. I've personally only taken classes taught by her, but I'd put my faith in any teacher she hired.
Classes here are unique in that it's challenging and fun all at once. You quickly feel like you're a regular and like you're hanging out with a group of friends who will support you - esp. when you're trying a difficult pose. Angelica also likes to incorporate fun things like flowers, tea lights, and live music, which def. sets this studio apart from other classes I've taken.
SCY is great about keeping an updated class schedule on their website, and classes are 90 minutes each. They're offered at a wide range of times, and once a month, the studio hosts "Happy Hour" sort of events where you do yoga and then drink. Kind of a great win-win.
If you're looking for a yoga studio in Vegas, I'd def. start here first!