Hi,
Sounds like a great trip you have planned! FYI the visitor's center at Red Rock Canyon is easily accessible so no hiking is needed to take in the spectacular views there.
I don't know how old your kids are but I took my son to see Tournament of Kings when he was eight and he LOVED it. I think it would still be fine for younger teens, but perhaps older teens might find it a tad cheesy, depending on the kid.
The Mac King show at Harrah's is a hilarious comedy magic act that is family friendly. I see there is a deal on Yelp right now (
https://www.yelp.com/deals/the-mac-king-comedy-magic-show-las-vegas-40) but some older posts on TA indicate it was possible to get free or deeply discounted tickets at Harrah's in the past, so that may be worth following up (
https://www.tripadvisor.com/ShowTopic-g45963-i10-k6693559-Mac_King_tickets-Las_Vegas_Nevada.html).
Shark Reef at Mandalay Bay has an amazing aquarium, and the Las Vegas Natural History Museum, although small, has a nice collection of dinosaur fossils and animatronic dinosaurs if your kids are in to that sort of thing. Springs Preserve is also a very cool nature preserve and desert environmental education center. The Atomic Testing Museum is also worth a visit.
Don't miss M&M World on the strip. Las Vegas has a local chocolate company called Ethel M that offers free tours of their factory and huge cactus garden in Henderson. Inside the Bellagio, there is a free beautiful seasonal floral/plant display and nearby is a pastry shop, Jean Philippe, with this crazy, elaborate chocolate fountain.
The free light show at Fremont St. Experience is super cool, but some of the people hanging out there are a bit shady. It's not unsafe, however--we don't have a problem bringing our son there, but YMMV.
Generally, for any paid show or attraction I'd like to see in Vegas, I google its name + cheap tickets and usually find links for discounts.