Green, clean, quiet, new - everything you want out of a SF hotel
I booked the Orchard Garden Hotel for my parents when they came to visit me in SF. The hotel is in a great location only a few blocks from Union Square, a few blocks from Nob Hill and 1/2 a block from the gate to Chinatown. The location is perfect because it avoids the craziness of Union Square and it is on a slight hill so the buses don't travel down Bush Street either. 
The hotel is only 6 years old and everything is immaculate with soft relaxing green and beige earth tones throughout the hotel. The beds are apparently quite comfy and the rooms are very quiet which is a rarity for being so close to Union Square. 
One of the selling points when I booked the hotel was the fact that it is one of the most eco-friendly hotels in San Francisco. 
The staff were eager to help with any questions and the restaurant had a nice menu and a wonderful butterscotch chocolate mousse dessert. They have a cute little rooftop area where you can sit and catch some rays or just chill out with some friends and drink a soda. 
I plan to recommend this hotel to all of my friends and family when they come to visit. If I didn't live in San Francisco I would certainly be staying there!