Hotel has a good location close to Union Square and public transport. We were disappointed with the size of the room and although the decor was styled 'boutique' found it to be dull and gloomy rather than vibrant and modern. (See photo of room). A friend who was also staying at the same time as us however found that the room size was fine for a single person. Decor wise the walls are a dull yellow with all paintwork green. In the bathroom the walls are custard yellow with green paintwork and lilac floor tiles. Windows and doors have been repainted numerous times and look like our own did before we got double glazing. Reception staff are very friendly and helpful but I don't know how they can see to do their work it is so dark where they are based. There is also a very old dog sometimes around Reception (does not mind a bit of attention), however he is allowed to sit on the chairs in the vicinity.
The beds were comfortable with 3 pillows on each, lighting was dim as is usual for hotels but there were lights above the headboards of the beds. The wardrobe is very small, only one side for hanging clothes which also held the ironing board , 2 robes and the suitcase holder; all of which had to be removed to try and fit the clothes in. The other side of the wardrobe should have had three shelves but we only had one in ours. There was an old long unit which held the television, underneath was the fridge on one side and 3 drawers (which stuck) on the other. It was very cold when we were there (San Francisco in August is like the worst of an English summer ) - lots of tourists were wearing jackets with San Francisco on - like us they had probably thought California in August would be hot and sunny but the low cloud makes it COLD! It was even four days before we could see the whole of the Golden Gate bridge. It is really strange because you can see Sausolito which is quite close and it is lovely and sunny there. Anyway back to the room - the heating (yes we needed heating!) is very noisy (probably an old system) and I wouldn't be able to sleep through the rattling it was making. There was no safe in the room so we had to put valuables in a security box at Reception and keep asking for access whenever we needed it. There was no coffee maker. The bathroom was well lit and nice and bright;with a magnifying mirror and hairdrier . Shower head was fixed to wall and was a decent strength. There was a full length mirror on the back of the bedroom door. There was an extending washing line over the bath which we made use of - only drawback was it took 3 days to dry things.

We did not have the free glass of wine as we were always out and about but it is a nice gesture and enjoyed by many I'm sure.

Things we enjoyed while in San Francisco and would recommend:
Alcatraz
But trips are booked up well in advance so book at least a couple of weeks beforehand - longer if possible to get a good time. I would suggest going in the early afternoon as the low cloud seems to clear by then and you get the best views, but the cloud does come back in later in the day (around 5pm when we were there)

Wine country tour
Very enjoyable, not just because of the wine but also the tours are interesting and you get to spend some time in Sonoma where you have lunch.

Sealions on pier 39
Great fun to watch them sleeping, swimming and shouting their heads off!

Boat trip to Sausolito
Also a lot of people had hired bicycles to ride over the Golden Gate Bridge and got the ferry back.
Whilst in Sauslito we got the local bus to Muir Woods where the giant trees are worth seeing.

Nightime:
Duelling pianos downstairs at Foley's Bar in O'Farrell Street.

Not recommended
Open top bus tour - nearly had our heads blown off. The bus does not go slowly and as mentioned above SF is very cold. I looked around the bus as we went over the Golden Gate bridge and everyone had their heads down, eyes closed or were burying their heads into their companion's coat! I felt like I couldn't breathe properly as the wind was taking my breath away so covered my nose and mouth with my hands.

AVIS car hire at Union Square
Avoid this company/office like the plague - we waited THREE HOURS to collect a car we had booked )along with numerous other people who were in the same position). Interestingly the manager had preprinted $25 disount vouchers to hand out - we assume therefore this happens quite often. We had a long drive ahead of us and Avis complelely ruined one of our valuable days in California.

In conclusion San Francisco very enjoyable but we wouldn't stay at the Rex again despite location.