As Tom_MN mentioned, the Jotunheimen Mountains, northeast of the Nutshell area, are as far north as Rick’s guidebook goes at the moment. He’s taped a TV episode that does likewise.
Rick’s books/tours/TV shows highlight the “best” of a country, geared for Americans with limited vacation time, to see and do as much as possible within that limitation. Some of the Norway book must be considering practical accessibility of places in a visit. Rick is the first to suggest that Lonely Planet, Rough Guide, Fodor’s, Frommer’s, and even DK Eyewitness guides are valuable guidebook resources, in addition to his. I’d add the Moon books, from his same Avalon Travel publisher, is another book to consider.
We’ve been to many places in Italy, Ireland, France, Spain, and Central Europe that Rick doesn’t cover. He used to say to not surprised that his books are thinner than others, and his readers like it that way. His books are getting thicker all the time, but are still selective about the content. With more time and interest, there’s more to see than what Rick can pack into his book, and ways to find out about it. His books are a great start, with inspiration to look deeper into destinations.