We understand it's your vacation too and we want you guys to experience Vegas without the restraints of typical wedding duties. We are just happy to have you guys there with us so show up for the ceremony and be ready for a good time!
I would say Casino Nights is the attire to go for, bring out the glitz and the glam. A little tacky but in the best way possible!
Obviously bring your significant other
If you're staying at one of the main hotel and casinos on the strip you can pretty much walk anywhere. I would recommend ubering to the ceremony though.