Wow.
I see there are a wide range of experiences at this property.
We spent two nights there in Summer 2008. We were upgraded to a very spacious suite. Not quite "Presidential" quality or anything, but big: a full living room with a conference table, couch, a couple chairs, and a big balcony. One of the 2 times in 2008 that Marriott put me in a true one-bedroom suite.
The lounge was open that weekend...I seem to recall that our room was directly above the lounge but I could be dreaming that...

I don't know: I stayed in a *lot* of Marriotts last year.
Front desk was helpful. We were attending a wedding one night, but also had one day free to do some tastings. The concierge gave us a stack of Free Tasting cards....about 10 wineries. We hit maybe 6-7 of them over the course of a day and a half - some good, some so-so. Two of the cards even included a free BOTTLE of wine...granted, those were not the top-end vineyards, but still...
Overall, the only reason I wouldn't necessarily recommend the property is because I wouldn't recommend ANY standard business hotel in Napa: if you have the option, go farther up into the valley to a B&B. Or perhaps the Renaissance in Sonoma.
We stayed at the Marriott because of a super-cheap weekend rate that we combined with a Premium Pounds to make the whole stay nearly free.

Without all that, we'd do a B&B.