The Hoover Dam is about a 20 min drive that is worth seeing. As far as in Vegas is concerned, depends on what type of scene you are looking for. There are countless bars and clubs that all have a different vibe. I am a big fan of all the small bars in and around the Imperial Palace Hotel almost 9 years ago
That is a tough question
You need to be more specific
Outdoor or indoor?
What kind of fun?
What kind of food, if any, are you looking for?
Someone looking for casual encounters will go different places based on age and preferences. People that hang out at the Hard Rock pool (think very fit) are not likely to be happy at Circus Circus unless it is for the Steak House.
Same for gambling.
Give us more to work with, you'll get a better answer. almost 9 years ago