You know, I sort of get peeved with this advice about Las Vegas being hot in the summer.
Well, yeah, like DUH, we're in the middle of the Mojave Desert, of course it's going to be hot in the summer!

It's kind of like saying watch out if you go to Fairbanks, Alaska in the middle of winter it might be really cold!
Does the heat keep people from coming here? Of course it keeps some people. But for millions of people, myself included, summer is a great season in Las Vegas.
Yes, it is going to be about 103F today and about 97 tomorrow and then back up into the 100+ degrees. We actually have a chance of thundershowers tomorrow, which does make it more uncomfortable, because it raises the humidity. Normally our humidity is under 10, so it is hot but not sauna hot, like much of the US during this time of the year.
But having said that, it's usually dry, very sunny and very pleasant. Everywhere is air conditioned. There are plenty of cool spots to spend a lazy summer afternoon. The evening do cool down into the 90's (lows in the 80's).
I see you are at the Flamingo, the pools there are a great place to spend the afternoon. They will be busy and hectic, but the water will feel great and the Flamingo hotel pool is about 5 acres of pools, very lush and nice. The pool at the HGVC is smaller and quiet, but has nice cabana's (free) with a fan and misters and there is a bar at the pool area.
Since you are non-gamblers, get to know our city. It's great you are renting a car, there is lots to see and do here besides being on the Strip. Many of us who live here rarely go the Strip except for special events/occasions. Las Vegas, is far more than Las Vegas Boulevard, though that is the primary image that people have of this town, which is sad.