Very recently stayed at the Chelsea Motor Inn for $79/night. Very clean and safe. Even has free covered parking and free wifi in the rooms. This seems to fit the bill except that it is not necessarily in walking distance to major tourist sights. However, boutiques, restaurants, cafes and public transportation abound. It's on Lombard between Fillmore and Webster.

We got the Grant Plaza Hotel for $88 and night booking directly with them. We also got the Marriott downtown (4*) for $110 a night through Priceline. Dates are for next week.