It can be as expensive and as cheap as you make it. The reason is that it is open competition for customers. Unlike places like Disneyland which has a captive customer base. They don't have competition and can charge what ever they want for things like food. Here in Vegas it is wide open. You can go anywhere you want to eat, shop and do what ever. That competition keeps prices low to attract customers. Also with the fact that Vegas is a 24/7 town they have special low prices on things in off hours.
No. Vegas is expensive as a tourist destination. I was just watching something earlier today about the swimming pools at some Vegas hotels. Some charge upwards of $10,000 for a section by the pool. Lemme see if I can find it....
Here it is:
http://abcnews.go.com/Travel/las-vegas-hotel-pool-sunlight-swimming-tourists/story?id=11739234
It can be cheap... as someone already stated, the competition is pretty high so the prices are somewhat cheap, almost everyone there tries to give out coupons and discounts to attract customers. Most of the places there make money through the casinos, so if you don't gamble - you can enjoy the atmosphere and great food at decent price.
I'm not sure Vegas is really a great vacation spot for families (with kids), it's kind of more adult oriented.