Major hotels near Moscone center are: the Marriott on 4th st between Market and Mission st, the Intercontinental Hotel San Francisco on 5th and Howard st, and the W hotel on the corner of 3rd and Howard....major credit cards accepted.
I stayed at The Park Central. It was reasonably priced and a couple of blocks from the Moscone Center. I would recommend it to anyone.
Moscone center is in valuable place. There is several hotels, because of frequent events, but often expensive. If you can, look for hotel close to, the palace hotel for example. Else you can look for hotels at several tramway station, like in Castro district.
There are quite a few 4 star hotels in the vicinity and walkable distance. Just do a simple gopgle search :)
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