Warning: High Taxes
I stayed at Sofitel for the weekend of Navy vs Army. At the time, it was the cheapest 4-5 star property I can find. The hotel was an easy 5 minute walk from Suburban station where AirTrain (possibility one of the cheapest and the most convenient way to get into the city center from the airport) dropped me off.
The hotel offers free daily Wifi, but my LTE was faster on the phone, so I never really used their Wifi. The room did provide Ethernet cable for those with a laptop, but I hardly ever travel with one even on business, so I can't comment much on the speed of the service. 
I had a regular one king room, the bed and pillows were super comfortable. The bathroom was large and equipped with Hermès amenities at the time, including a nice hair dryer, cotton swap, nail filer, needles and thread, shower cap...etc. There are coat brush, iron, and slippers provided which was a nice touch. 
The location of the property was perfect. It puts you right smack in the middle of the city. I walked to the Independence Mall and Old City area no sweat through lots of attractions such as Reading Terminal Mall and Chinatown. I also walked from Chester down 9th street through the Italian Market and compared Geno's and Pat's. A walk up to the City Hall, Love Park Christmas Village along Benjamin Franklin Parkway though Comcast Center to the Philadelphia Museum of Art was also a breeze. The hotel was also close to a CVS which made daily drink purchases simpler. To the southwest, you get Rittenhouse Square, which made more leisure walking possible.
In Philadelphia city center, I suppose the hotel charges two taxes, one of the most ridiculous thing I ever heard. Especially coming from a city where we are used to a ridiculous amount of taxes. So please know that you will be charge a 7% tax plus an 8.2% city tax. So be prepared for paying about almost 15% just in taxes. for me that's over 200 dollars for 3 nights just in taxes. It's ridiculous yes, but I guess you can't argue much with uncle Sam.
During our stay, a false fire alarm went off at 1am, we were all outside of the hotel in the cold and rain for about an hour, the hotel did verbally apologize for this, but no physical apologies or deduction to our room-rate. I expected some discount for being woken in the middle of the night standing in the rain in my PJs for an hour. But none was given. Which left a negative mark in my experience.
Overall, next business trip to Philadelphia, I may try AKA Rittenhouse Square down the street. As for Sofitel, I think it is extremely overpriced for what you get.