My husband and I traveled the world for 18 months and, as you can imagine, stayed in many hotels along the way - few stand out anymore now that we are home. But the Rittenhouse is an exception - the service is incredibly attentive, to giving my very sleepy kids presents from the "Treasure Box" when we arrived, to helping us with our car, directions, welcome cookies, etc.
Most recently, my husband discovered he left his shoes there, and almost a month later (of course, he didn't tell me until now) they located them and promptly put them in the mail. If you've ever lost anything in a hotel before, I'm sure you agree that this almost never happens (actually finding them, and then having them sent to you).
As for the rooms, they are big, and comfortable. Even with four of us in a deluxe room (one bed, one pullout, and a crib), we slept great. The bathrooms are large and luxurious. We had a nice view of Rittenhouse Square.
Basically, it's hard to put your finger on the one things that was great about it - because so much was - but I left the Rittenhouse feeling refreshed and happy, which is a sign of a great stay.