Believe me I considered this option. If I was okay with losing about $3,000-$5,000 then it would have been feasible. I wasn't okay with losing that much.

Surprisingly, taking that large amount to Hong Kong and changing at Chunking Mansion was the best option. Make sure you bring your passport as the currency exchanger must make a copy of it. I was a little uneasy at Chunking Mansion with that much money, but Hong Kong is a very safe city. They usually have a police officer at the entrance. But I'd be lying if I said I wasn't sweating, and constantly looking around to see if anyone was watching me when I changed the money at the currency exchange hut. The second money changer when you enter Chunking usually offer the best rates. The first booths rip you off. I didn't lose any money, and the declaration upon entering the states was fine. In fact I got a very nice customs officer who made the process seamless.

If bringing a large amount of cash into the states, and declaring, I also would recommend carrying the casino loyalty card, the casino cage's number, your casino hosts number, and any other things you can gather from casinos such as a W-2G (if you have). I also carry lots of books on poker, blackjack, and gambling to prove I do this for a living. This will prove you won the money at the casino, and you're a regular gambler, and they won't seize the money and claim it's proceeds of crime.