Broad Street divides Center City into East and West. Center City East lies just west of Old City and Society Hill. It is home to the convention center, Chinatown, and Washington Square West (also called the Gayborhood).
There are plenty of good chain hotels on and near Market Street that cater to the convention crowd, including the Wyndham, Hilton Garden Inn, Holiday Inn, and the Marriott. Great bed-and-breakfasts can be found near Antique Row in Washington Square, and there are also a few independent mid-range, mid-size hotels nearby.
If it’s gay culture you’re after, Uncle’s Upstairs Inn [1] and the Alexander Inn [2] are two excellent choices.
Links:
[1] http://www.moon.com/destinations/philadelphia/hotels/center-city-east/100-150/uncle-s-upstairs-inn
[2] http://www.moon.com/destinations/philadelphia/hotels/center-city-east/100-150/alexander-inn