You can dress casual even if it states there is a dress codes it doesn't appear to be enforced.  

Xo LaRue

If you leave the kangaroo in the car you should be fine.,

I was just there and I didn’t feel that there was a “dress code “. But if you use common sense in how you dress then you’ll be ok. Bare feet and tank top might be questionable.
I wouldn’t give it a second thought
Now some restaurants I can see it …

I stay there often... beautiful property with a nice clientele.. the dress code is not enforced but I feel you will feel better if you wear a nice shirt or polo shirt with shorts... dress casual but nice..

Pool attire and athletic wear is fine around the Wynn as long as it looks good. XS usually has a nightswim on Sundays over the summer. Otherwise look your best