Yeah, it's really hot out here for your average out-of-towner so swimming is fantastic, but anything else outside is probably best done at night. Karaoke is great, dollar blackjack at the Sahara is fun, especially when you're getting free drinks, barbecues might have to planned if you're doing them at a park, and you have to ask them if you plan on bringing alcohol unless you make it obscure I suppose. If we go the park I'd be down to set up some slacklines which are basically like tight ropes but they wobble quite a bit if anyone wants to try that.
I mean, the heat isn't so bad if you're dressed light and stick to the shade -- maybe hang at the park, but yeah, it'll probably be too hot for anyone sporting a monitor tan.
Also, I can guide a small group of 5-10 around Red Rock at night if anyone were interested in that (it's a sight to see, and definitely an under-looked aspect of Vegas), but unfortunately you aren't allowed to start fires out there to make Smore's or something unless you want to risk getting a hefty fine -- though I have done so before a of couple times.