This should help....
https://www.vegasmeansbusiness.com/planning-tools/convention-calendar/?formid=2&e_sdate=07%2F01%2F2015&e_edate=08%2F31%2F2016
At a quick glance.....
7/10-14th 27k conventioneers at Mandalay bay and 12k at Las Vegas Convention center.
8/2-5th 44k Conventioneers at the Las Vegas Convention center and 50k at the World market center.
looks like those 2 weekends, you def want to avoid Vegas!!
I don't see much of anything special the last weekend in August other than 5,000 attending at convention at the Las Vegas Convention center (8/24-9/7)