Later in Spring - over a month away - I will be in Las Vegas for a few days for a work conference. I've never been at all before, so I'm curious as to what I should expect & wear. Here's a bit more info:

This is a professional event centered around a topic that I am trying to learn more about. I am more on the "guest" side of the event, not on the "sales" side (as some of the other attendees will be representatives from vendors who we either use now, or who would like to obtain our business, and they tend to dress more professionally.) I went to a similar conference held in my home city of Seattle a while ago, and the dress code was pretty much standard business casual for people in my position.
However, one of our vendors has also scheduled an evening event at what looks like a very fancy lounge club at one of the major casinos.

I will also be taking a couple personal days after the event is over with to spend some time there with my boyfriend, who has been to Las Vegas several times. I don't think we would do anything particularly fancy - he is a strictly jeans and tee shirt kind of guy - but I would like to see at least one major show if we can make it work (such as Cirque du Soleil.)

What sort of wardrobe would you recommend given the weather & the events/setting in question? I know this is a ways off, but I would like to plan ahead.