I used to live in Las Vegas, but we only go back to visit family.
Vegas tried to be "family friendly" a few years back, but they've pretty much given that up now. There are some arcades and attractions for kids, but geared more toward school-age and high school, IMO.
The hotels are very crowded, very loud, and very smoky. There is no such thing as a non-smoking casino, and even if you just walk through the casino to the restaurants or shops, it still stinks!
It is also really hot. I don't know what the climate is like where you live, but it's consistently at or over 100 degrees in the summer. The plus side is, every building is air conditioned!
There's a M&M store on the strip, some interesting malls to walk through, an Ethel M chocolate factory with a mini-tour.
Everything is just really crowded. We don't go near the strip when visiting our relatives. Wall-to-wall people, which I know you get at Disney too, but at least at WDW there aren't people walking around with drinks in their hands, or passing out advertisements for strip clubs. I'd want to keep a toddler in the stroller most of the time, and my kids would go crazy cooped up like that every day.
Although they may have changed the laws about drinking on the Strip and passing out that stuff. There are some questionable billboards though - for the strip clubs and cabaret acts. Now that my oldest can read, we get some really embarrassing questions "Mom, why does that sign say 'Live Nude Girls XXX?"
A long weekend, maybe, but I do think a whole week in Vegas would be boring for a toddler.