Marriott Gold Member Review - WOW!
I stayed in San Francisco with my fiance for a romantic weekend getaway. Let me tell you..THIS is one of the nicest Marriott's I have *ever* stayed out. This property is right on par with what would be expected from a five star property at four star prices. Yes, the valet costs $49 per night, but you are truly paying for convenience and service. I would always call right before heading downstairs, and my rental car was pulled around with the doors open ready to go every single time. The lobby was gorgeous. The room was WONDERFUL! The bathroom is all marble with an separate tub (complete with its own hand shower wand) and shower stall. The room was soooo comfortable and modern. The San Francisco temps made opening the windows and obtaining fresh air a wonderful thing. The best was yet to come on this *weekend* trip when I headed up to the concierge lounge. Yes, it is open for breakfast/appetizers/drinks/dessert during the weekend. What a value!! 
The convenience and proximity that Union Square offers is perfect. The rooms are a little pricey, but again I believe we received a five star value. Enjoy your time in San Francisco, and don't worry about your accommodations if you have confirmed reservations at this property. You will impress your significant other, and have a wonderful time.