The Union Square Plaza is the the best budget hotel. Very friendly staff and there is free coffe every morning and there are hundreds of cafes and restaurants nearby! The hotel has amenities that you would nor expect from the price: Change of sheets and towels every day, big room with ensuite bathroom and cable TV.
Everything is nearby, Union Square with all the shops,Chinatown, Market Street and the Ferry Building with beautiful shops and for ferries to Sausalito. If you want to go further, buses,streetcars, subway and trains are maximum 5 minutes walk away!
Also, exactly opposite the hotel are two very good theatres and all other theatres and main cinemas are very close.
I would definitely recommend this hotel to any traveller of any age and pusprose travelling to San Francisco. I can not wait to visit it again myself!!
Pros: Inexpensive, Close to everything, Big and clean rooms