Credit card companies are very sharp about picking up fraudulent transactions. They are quite aggressive about it because they rarely pursue amounts below $5000 - $7000 in collections or court. It's not worth the fees and manpower, so they would rather catch it before it happens.
It's a great idea to let your company know that you are traveling abroad, although I have seldom had trouble with it. They learn your travel and spending habits and adapt very quickly. I spoke with an American Express rep one day and during our conversation he mentioned that the computer programs that they use are quite accurate at picking up fraudulent charges, but the also use humans to detect fraud.
As far as stashing away cash, I never have, and neither do most of the people that I have traveled with. I always keep any cash on my person. If your cash is not on your person, you have no way of detecting or defending against a theft until it is long gone. That is one theory, of course. Putting cash in your bags will give you additional cash if your person is robbed, but hiding it anywhere in a bag is easily detected by someone who is actually trying to steal something. Of course, it might deter the opportunistic thief who is not really looking to steal, but can't resist a shiny Rolex watch or a stash of $2000.
Cash in the front pocket, the pocket nearest the waistband, of deep-pocket pants (long or shorts), is almost impossible to steal without force. You would actually have to be mugged. Of course it goes without saying that the less cash you carry, the better. Your debit card, if you choose to carry one, should be handled as carefully and securely as your cash. A stolen debit card, even with a VISA logo, can empty your bank account very quickly. Credit cards are the best, as there is practically zero risk. Of course, not every biz takes credit cards.
Now for the funny story...
I was set to fly home from Houston to Saint Louis. Right before I got to the airport, I topped off the rental car with gas. I was so late that I almost missed the flight, so there was very little lag time before I departed Houston. I landed a little over 1 hour later in Saint Louis, no checked bags, first off the plane, and was in my own car about 15 minutes after landing. I filled my car up at a gas station about 3 miles from the airport. I clearly remember -- I was at the stoplight waiting for green right outside the gas station, less than one minute after getting my receipt, when my phone beeped. I don't talk on the cell in the car, so I waited until I got home and checked the call log. It was American Express saying my card was shut off and please call the fraud dept. The rep said that the computer immediately recognized an anomaly and shut the card off, then notified the fraud dept. The computer basically said there's no way that I could have driven from Houston to Saint Louis in 2 hours (remember the two fill-ups?).
