I'll be in Vegas next week for a friend's birthday party and it just happens to coincide with Twice's concert. I figured it would be sold out by now but turns out there are tons of seats available.
If you buy a lightstick, your next immediate purchase should be ear protection. Hearing the concert at full blast is not worth the damage it'll cause if you're not wearing earplugs. I had 24dB filtering plugs and could hear the concert perfectly fine, in fact I preferred it that way haha