I drove by the Sheraton Sonoma County - Petaluma just yesterday, but that's as close as I got to it. Sure looks nice from the outside!
There was also a Four Points (also off of Highway 101) not too far from it. But I've got no experience there either.
You might use the FlyerTalk "Search This Forum" feature on words like "Napa" and "Somona" as there have been several threads on these properties in the past.