How much cash should I bring for a week in Las Vegas?

The hotel, airfare, and car is already paid for. We already have two shows pre-paid for as well. basically, I am wondering how much cash I should carry for the sake of impromptu events, meals, souveniers, etc... I was thinking $1000 and then keeping 500 in my checking account for debit purchases with my VISA debit card. Does this sound restrictive or reasonable or too much? Thanks for the tips! I haven't been there in 26 yrs!!!