Circus Circus is the cheapest [and the smelliest]
no matter where you stay it's gonna stink like cigarrettes!
I just got back from their today.
I highly reccomend you watch a show called "Le Reve" it is the most amazing thing I have ever seen in my life. Your kids may be scared if they watch "Blue Man Group" I am thirteen and I was a little scared.. haha.
and you can possibly stay at "New York New York" [my favorite]
In Circus Circus, go upstairs and there is a fun arcade where you will need lots of dollar bills, and your kids can play and win lots of stuffed animals.
You can take a little boat ride in front of the Venetian, and the guy will sing for you.
Oh! and I almost forgot! Take the Mirage tram [2 minute ride] and exit, and look at the signs and follow to the Secret Garden. There are Dolphins [baby dolphins too!], lions, tigers, and it's just plain amazing!
Your kids will like the Secret Garden.
Oh and don't forget to visit this cave thing with lots of attractions! There's tons of kids there. I don't remember what hotel it was in though.. sorry. Just ask someone. :)
Also go to the store called M&M World - it's a tad expensive but cool.