We stayed at the JW Marriott in downtown San Francisco for 3 nights in Sept. The location of the hotel is perfect, just 4 blocks from the BART station, in the midst of Union Square with lots of chain shops but also some boutiques, great restaurants, theatres and at least one nightclub. A new Bloomingdales opened up a couple blocks away the week after our visit.

The lobby and reception areas are very nice. The room was nice size (we had a double double), large bathroom with a tub and separate shower. The furniture and carpet in the room do need an update and this is my sole complaint with the hotel. But the beds were very comfortable, the windows open, and the a/c was incredibly quiet. Front desk, doormen, and housekeeping staff were all very friendly and courteous. Turn down service was a nice touch.

Our stay was September 21-24th. We used the BART from the airport and walked about 4 blocks to the property from the Powell Street Station. We discovered this was a great central location and a good value for the price (after comparing to other properties in the area).
Quick, friendly check-in (which was true of all of our experiences with the staff - they were friendly, gracious, helpful, respectful, knowledgeable and observant). Room service was quickly delivered our first night. The room was clean and daily maid service was excellent, though I agree with a previous post that the room itself is showing some minor signs of wear and tear (scuff marks, start of peeling wallpaper, etc); also, the mattress "pillow" seemed a bit worn and not nearly as comfortable as other Marriotts where we've stayed, but it was adequate and not important enough to report to the management. Otherwise, the room was spacious enough for two of us to prepare for the day each morning and comfortable enough to stretch out in the evening. Loved the bathroom setup (didn't watch too much TV in there though).
We did get a nightcap & dessert one evening for our only other exposure to the hotel's food & drink offerings. Service was up to previously mentioned standards and a delicious bread pudding satisifed my wife's craving for sweets.
To accomodate our late afternoon flight home we asked for and received an extra hour to check out (1pm). It was generally a nice experience.

Last April, Marriott took over the previous Pan Pacific Hotel, a luxury hotel on the corner of Marsh and Post streets just one block away from Union Square. The choicest of all locations in our opinion. We had stayed at the Pan Pacific and thought it fine, but already...in just 5 months, Marriott is showing a deft touch at improving the property. Your greeting at the front desk is full of smiles, your room immaculate with valet services and a turn down service. Breakfast was the best hotel breakfast we have ever had and the doorman and garage attendants couldn't have been more accomodating and friendly, An absolute hit with us and already a big improvement. Marriott has two hotel properties down by Fisherman's Wharf. This is their first luxury property in the City of San Fran. And they can be proud of it already
Arroyo Grande, CA

I stayed at the JW Marriott Sept. 4-8th with my mom. I booked this hotel through Priceline for $90 a night so this was an exceptional deal considering the rooms go for $200 plus a night. They were gracious enough to accomodate my room request of 2 doubles and non-smoking (although the hotel was scheduled to go non-smoking at the end of the week anyways). They also gave me a late check-out (2PM instead of noon).

The room itself was very nice. The beds were extremely comfortable, and the bathroom was very nice, although I would have forgone the large sunken tub for a roomier shower and a second sink. (With 2 women getting ready in the morning, a second vanity is always nice). The shower was pretty small and was hard to maneuver in. Water pressure was just okay. The tv in the bathroom was a nice touch.

Our rooms were always cleaned when we returned at night and turndown service was available each night. I did call the front desk the first morning because I was having trouble with the hairdryer. Someone was at my door with a new one in just a few minutes.

Although my requests were always pretty simple and mostly direction oriented, the concierge was extremely nice and always happy to help with a smile.

This seemed more like a hotel suited for business travelers, but it works just fine for tourists as well.

I would recommend this hotel. There are several starbucks within a few block radius - it's just 2 blocks from Union Square and the Powell Cable Car turnaround, and near lots of shopping.