Stefan'tly a good hotel.
Thon Hotel Stefan is a nice place with friendly staff. It's right in the centre of Oslo and seems to be fairly close by to everything you'd need.
Internet connections are available in every room, though not free. However, there are two computer's down next to the lobby which provide free internet - which proved useful for keeping in touch with people by email, uploading photos to Flickr and blogging about the holiday on Opera Community.
Whilst the hotel is not in the immediate vicinity of clubs / nightlife / loud music, and more of a walkable distance, Saturday night was a particularly loud night for a local music venue - but it didn't keep me awake.