Vegas must do's... any ideas?

Okay ill make it short cause I'm on my phone anyway, me and a buddy r gonna be goin to vegas this winter. Ill be 22 hell be 21 what are the must do's? I no bellagio fountain but what else? Hoover? NY NY rollercoaster? Stratospher rides? I'm just not sure what the cool things to do are. Thanks 4 ur help!!!!!!