Per the T&Cs from Marriott's website:

"Marriott Cheques may be used for all publicly listed and available room rates and packages, but cannot be used for convention, travel industry, tour, advance purchase, catering, or group room rates."

So I guess it depends on how Marriott looks at corporate rates as to whether they should normally except them. Given that MDXman was successful in using them on a corporate rate, I guess Marriott considers those to be "public" rates.

The other question of whether this is the "best" use of points is really a personal one. It depends on how you would have spent your money or points if you wouldn't have used them on these rewards checks.

If you have tons of points and you would have put down $1000 toward a stay for spas and other "extras", and by saving that $1000, you can now do something, buy something, or go somewhere, you wouldn't have been able to otherwise, then this may be a great use of your points.

But in terms of calculating the pure value of your use of points though, you would get more "worth" by saving your points and purchasing a travel package that included airline miles. That would allow you to take a vacation possibly worth $3-5K or possibly more even. So if you use your points to purchase $1K in checks, but then turn around and spend 4K on a family vacation that could have been "free" using points, then maybe you aren't using your points in the "best" way possible.

So again, the real answer is what value to you feel you received from your use of points? No matter what persons here or anywhere else say, if you can enjoy your use of points and come away with a smile on your face, then it was probably a good use of points.