Matt,
The thing about Carpathia was that she was built not for luxury, but economy. Equipped with large refrigerated storage compartments for food, as well as second and third class areas, she had no first class! I imagine the fact that the ship was a dual-purpose friegter/liner might have driven away the 1st Class passengers, so Cunard simply nixed the idea of a premier class. Ironically, Carpathia was one of Cunard's biggest ships, a mere 1000 tons off the size of Saxonia! It's rather amusing such a large ship had no first class!
Getting back on subject, the interiors were nothing extremely special, owing to its two-class distinction. However, she was a well equipped ship for her time. 3rd class had a bar, sitting room for the ladies, smoking room, and a 325 person saloon. (This seems small considering it could hold 1500 3rd class passengers) 2nd class could only hold 200 passengers, so extra facilities were meager. However, it is said that they were tastefully appointed.
Hope that helped!