Wow best promo ever. Too bad I quit my job Sept 19 and left Puerto Rico. I was switching hotels daily to max this out. Now to cash out the 6 nights of bonus I got, not to mention the Orbucks I legit earned. As for stacking, it looks like terms of TopCashback and friends say that you get the 7% on undiscounted rates. So if you apply the Orbitz 10% off code, you only get 1-3% back. Makes sense....there is only so much money to go around. So you have to choose where you want the bonus.
Thanks to folks for mentioning you can book now and lock-in the credit. I thought I needed to use in 60 days. That would have been OK, but I'm now somewhere where AirBNB is better, so best to save it for some USA travel during ski season.