Are you sure you're not mixing up the JW Marriott with the San Francisco Marriott? The JW has only 320 rooms, while the SF Marriott (which is much closer to the Moscone Convention Center) has 1500 rooms.

All three hotels originally mentioned are within two blocks of each other, either facing or within a block of Union Square.

The JW (originally built in the later 1980s as The Portman Hotel and later the Pan-Pacific Hotel) is much more upscale than the other two (and therefore the more expensive). John Portman designed and built it as the flagship of a proposed chain of upscale hotels (which never took off), which explains the larger-than-normal room sizes.

The Grand Hyatt (opened in the mid-1970s as the Hyatt on Union Square, on the site of the historic Plaza Hotel) is a typical 4-star establishment - upper floors have decent-to-good views (especiallt those facing southward).

The St. Francis is the historic member of the group. It was built in 1904, and was completely rebuilt after being gutted in the 1906 earthquake-fire. The tower was added in the early 1970s. As noted above, the rooms in the historic building vary greatly, while the tower rooms (some with good east-facing views) are more uniform.