I stay in upwards of 50 hotels per year and very rarely award any of them 5 stars, but Andaz Napa is more than deserving. The hotel is beautifully decorated to capture the rustic charm of Napa will providing cutting edge amenities like rainfall showers, state-of-the-art iPod docks and more often than note two-TVs per room.
The bathrooms are large and the beds are bigger (California Kings instead of plain old Kings). The lobby is large and spacious - with daily wine tastings (and a free glass when you arrive). Ordered room service one night but never made it to the restaurant. I will see the bar functions as a coffee bar in the AM and the coffee is fantastic.
There is a beautiful roof space where you can enjoy wine from your favorite vineyard during the day (the bar doesn't open until 5PM) or cocktails before dinner in the evening.
Concierge was helpful to arrange transportation and help with some dinner recommendations though we used a private concierge for vineyard tours.
There is no fitness center but full access to a gym next store which isn't the most modern facility in the world but very well-equipped.
Minor issue: we booked 3 months out and they were all out of rooms with two beds, had to go with a king / pull-out sofa. Not a big deal, just something to keep in mind. Also, every room seemed to be pretty different. We had a few (big group) and all but one had a fireplace and the one without it had a balcony. So ask about room type when you book.
All in all, an excellent hotel that maintains the charm of a small B&B / boutique hotel while upholding the customer service standards and luxurious amenities of a chain.