We are going to Vegas for 5 days, what are some things we HAVE to do there?

We are going to Vegas for EDC (Electric Daisy Carnival) which is 3 days (Fri, Sat, Sun 8pm-7am) but we are getting in Thursday at noon and leaving Monday at around 8pm. What are some things we HAVE to do in our spare time there? I was thinking shopping at the outlet malls, eating at this place called Firefly..? And we wanted to see a show but the times don't work. Where are good places to go to party and where are good places to hang out? We are going to Encore pool party Saturday during the day. It'll be mine and my boyfriends first time there being over 21. Suggestions? Thank you!