I'm taking my first trip to Las Vegas in October. I'm treating myself and a provider to dinners and shows. When traveling do you bring cash with you for her, it will be a tidy sum , or make ATM withdrawals?

ATMs in the casinos have hefty fees. So unless you want to pay $8-10 for ATM withdrawal you are better off carrying a small bundle, or use a bank close where you are staying.  

I used to bring 20$ with me on trips and keep it in my pocket.   Now with those scanners, you have to have it in hand.  (I'm not going to risk it in my carry-on, or certainly not in checked luggage.)

I carry large amounts of cash to Vegas every time. Never had an issue. My friend did get stopped in TSA for it but they just told the guys "I'm headed to Vegas" and that was that. A cashier's check might be best if you're worried about carrying that big of an amount. Probably cheaper than all the ATM withdrawals you'll make.

I have been "caught" with as much as $50,000 leaving Las Vegas and it's never even raised an eyebrow  

Seriously,  it's up to your personal comfort level.  Is this tidy sum more than you want to carry,  and less than your ATM limit? As others have pointed out, TSA can harass you depending on the amount and even alert LE who may try to seize the cash, but I doubt you'd be the first guy flying to Vegas with a huge sum.

Unfortunately LE can and will seize large amounts of cash. Then you have the burden to prove you had a legit purpose in order to get it back.

The fifty grand or so I sometimes carry in cash when in Vegas is chump change compared to real gamblers.

Like I suggested.. Get an account with BofA or Wells Fargo. Put the money in it, and withdraw from Las Vegas.. There are quite a few close to the strip, and even off strip..  When he is done, whatever money is left goes back in the bank account.. Its easy, and safest way to go about doing things..

Thanks for suggesting that I open a bank account
It's practical and useful for future trips.

When I travel, except to someplace like Vegas where I bring more, I "normally" travel with somewhere between $5-10K in cash. I rarely have to go through the scanners where you have to totally empty your pockets and then stand there with your feet spread apart and your hands above your head with whatever you had in your pockets in your hands, but when I do, I always put EVERYTHING in my carry on except for my ID and my ticket/boarding pass. I have NEVER had an issue with cash when doing this, not in literally hundreds of trips, both international and domestic since 9-11.

I always put my fun money in an envelope that goes inside my carry on laptop bag. For some trips (especially places like Vegas) that can be $3,000-$6,000. When going through TSA, I put everything in my pockets into my bag - wallet, keys, cash, watch, rings, etc. I only have my tickets and ID in my hands when I go through the Cancer-Booths.  

I wire money into my casino and withdraw when I get there.

This is what I do as well.  I have never used my bank for withdrawals but it comes in very handy for making deposits after a good night at the tables.  As others have said, just bring your cash with you, lock it up with a TSA lock in your carry on before the security check, put it in your wallet once you get on the plane and lock it up in the hotel safe once you get to Vegas.  If you’re bringing a large amount of cash that makes any of this uncomfortable for you, than having a bank in Vegas, where you can make cash withdrawals, is an even bigger plus.  I don’t use debit cards at all but there are plenty of big name banks with (BoA, Chase, WF) with plenty of branches scattered close to the strip that are convenient to get to for deposits or withdrawals.

if you are in a position to remove thousands a day from ATM  you should have arrangement with your bank not to pay ATM fees even when you withdraw from a casino ATM ....  i once had a $80 fee when taking from a strip club ATM ..   my bank chase reimbursed me      

what if he wants to go to different casinos owned by different holding companies ? Then not so much, is it..

I NEVER carry more than $10K  on international flights NEVER.  

I have a friend who will wire money to say MGM Resorts/Bellagio, the hotel where we're staying. When we arrive he'll go to the cashier, sign a marker for XX amount, get the money, they we'll cross the bridge to Caesars and fuck around over there.
I never seen him have a problem...it looked easy.

It's just like having markers at one casino, there is nothing preventing you from signing a marker for cash in one casino and then walking across the street with said cash to play it at another casino.

And he doesn't want to walk around with the floor with a wad full of cash, he can go to any gaming table, flag the Pit Boss, and sign another marker for X amount. Only thing here is that they'll "Chip" you out and you won't get cash, but shit you're gambling, right?
But wiring is the best if you're paranoid about carrying alot of cash.

I would wait until you arrive in Las Vegas, then give the provider the whole lump sum.  

There is no limit on how much cash you can bring into the US when flying in. The only rule is that if it’s more than 10k - you just have to declare it.

but in my case I have literally HUNDREDS of trips to South America, the last thing I need in my life is to be flagged as a drug runner  which would be a logical suspicion of a guy who is constantly traveling to such places as Bogota or Medellin, carrying large sums of cash on him.