Vegas In Just A Week

As of today I have done exactly no prep for the Las Vegas trip. I did buy a travel guide, but I haven't read it yet. I expect we'll do that on the plane.

Thing is, I don't know what to bring. Two things I don't own are shorts or a bathing suit. Will I need these? What else will I need? I don't expect we'll go anywhere super-dressy, but are jeans or business-casual okay in most places?

If I have to buy a bathing suit, I want a womens' black Speedo tank suit, just like the swim team wears. I'm too fat for a bikini and too cool for an old lady bathing suit. But I don't mind looking like a lifeguard.

Help me out, peeps. What to wear in Vegas?