Radisson SAS Nydalen Hotel

This is a fairly new hotel (won best new hotel award in 1998) and well up to the standard you expect from a Radisson hotel. It also offers excellent value for money: we paid 750 Kroner per night with breakfast for 2 adults and 1 child, booking direct on the hotel's own web site 3 months in advance (and for a Friday or Saturday night would have been only 650 Kroner). This price is a whisker better than any deal possible via one of the many discount hotel web sites.
The room we had was one of the 15 rooms specially designed for disabled guests - I guess these rooms may be a little larger, and we may have been given it because we were a family. The room was tastefully decorated in an African style and had a nice view. All fittings were of a high standard and breakfast was very good. Staff were helpful when asked various questions about Oslo.
Hotel location is in a modern business district, some distance north of the city centre. If coming by car, that may be a plus (it is easily reached from the Ring 3), and the hotel is directly opposite the Nydalen underground railway station.
Although not really a central location, it is nonetheless good for the tourist. Most will in any case want to have one whole day at Bygdoy where half a dozen of the top museums are located, and Nydalen is a handy location if you want to visit the Teknisk (science & technical) museum, which we enjoyed. If you intend to visit lots of museums, the Oslo Card is recommended: this includes most museum admissions and all public transport and car parking in municipal car parks. However, I advise against buying it before you go, because this will probably just give you a voucher which you need to exchange for the ticket proper at one of the two tourist information offices. Much better to buy it when you arrive, at wherever is convenient, including all big hotels; we bought ours at the Maritime Museum.
Eating out is expensive everywhere in Norway. One tip to mitigate this is to order tap water, which is a normal thing to do in Norway, and always tasted good. In most European countries, this is either frowned on, or you just wouldn't want to drink it! We had a good dinner at the Thai restaurant a few doors down from the hotel.