When we went to Vegas in '12 my favorite things were the hoover dam, Red Rock Canyon, Fremont Street Experience at night, and the Olympian show in the mall at Cesar's Palace (near Cheese Cake Factory - not sure what the actual show was called but it was free and it was in the common area of the mall). I didn't give 2 shits about the rest of the place. BUT - I don't gamble / drink / smoke AND my back went out so bad while we were there I could not leave my room for 2 days. Weird that we wound up moving to this area later in life but life is a funny business.
Now that I'm a 'local' (live in Nevada) my favorite places are The hoover dam, Death Valley Park, Red Rock Canyon, Valley of Fire, & Ash Meadows nature preserve. I also disagree about not bringing your girl, it depends on the girl. My wife and MIL both loved the Dam park and the exhibit center.
Also, and I am not joking here, EVERYONE needs to experience the Sphere. It's like IMAX on steroids. I'm actually looking forward to the remake of the Wizard of Oz that's supposed to start this month. That's assuming they didn't totally fuck it up.
EDIT: Fuck I didn't realize I'm repeating myself - damn thread necro!