Hotel Carlton, $79 per night? Bullshit! Its rate on Expidia.com starts from $139 per night, ok?
Hi, AshAsh, I have checked on Google Map and found that the Union Square is just within Downtown San Francisco, with a lot of restaurants, entertainment and shopping nearby. So personally, getting a decent yet cheap hotel within this area is really not an easy thing :(
I have searched online for a good while, but still failed to find cheap hotels under $100 per night close to Union Square. Personally, I suggest you to give a thought to other districts. Listed below are several cheap yet quality hotels close to Downtown area.
Americas Best Value Inn & Suites-San Francisco/Golden Gate
Best Western Civic Center Motor Inn
Comfort Inn By the Bay
Holiday Inn San Francisco
Or you can click the following link for more options: http://www.sanfrancisco-hotels-ca.com/ch...
Hope anyone else can give you an exact answer! Good luck!