There are many cruise lines that visit Norway, while we were in various ports we saw Costa, Princess, P&O, Azamara Club, Celebrity, Royal Caribbean and many other smaller ships. The prime cruise season is short, when we asked about going in early September most advised against it because of the cooler weather, shorter days and as I've found after, some of the excursions aren't offered after a certain date.
We ultimately selected Cunard's Fjord and Waterfalls cruise on the Queen Victoria because of the timing and the itinerary which included Flam and access to Norway in a Nutshell, the tour I've heard about for years. Plus it left from Southampton instead of Copenhagen, the airfares into Copenhagen were extremely high not that London fares were that much more economical.
People who cruise on Cunard expect that their fellow passengers will want to play dress up just as much as they do, if you do not care to dress formally this might not be the line for you. Every night was elegant casual, semi-formal or formal, most men wore tuxes on formal nights, women with long dresses. To eat in the dining room, men had to wear a jacket on all nights. There was a buffet style restaurant where you could eat if you didn't care to dress up but if you wanted to go to the shows or common areas, proper dress was expected. Dancing in the Queen's Room was very popular, we stayed out of their way with our minimal skills.
We got a balcony room, it was too cool to sit out there and most nights we would watch the scenery go by from the gym so I don't know that it was necessary. I'd at least go for a window though, I find inside cabins to be disorienting. There's a higher priced section called The Grills, I didn't even look into it so I don't know how much more expensive it was. We booked very late, by the time we booked they were offering great deals, Cunard was about the same price as Royal Caribbean.
Other than the fancy dress requirement, I didn't find the Queen Victoria to be much different than any Princess cruise we've been on, the ship layout is the same, the activities are similar. There's a gym and a salon, daily trivia and bingo and nightly shows, none of which we attended. There's only so much you can do with a cabin, I'm pretty sure ours was about the same size as the equivalent on Princess.
Not that it matters to me, but Americans were definitely in the minority on our cruise, I think we might have met 3 or 4 others during the week. Mostly British with a smattering of many other nationalities.
There's not a huge amount of information on Olden as a cruise stop, Cruise Critic didn't even have a page on it although you can search the forum boards for some information
If you want to see what other cruise ships are in town on the day you are visiting, check Cruise timetables
There were two cruise ships docked on the day we were there, the other ship was docked but we were anchored and had to use tenders to get in.
Favorite thing: Since no one would tell us anything about the public bus and the town's only ATM appeared to be a 10-15 minute walk from the tourist office, we decided to change money at the tourist office. The rate was not favorable, I think the official rate was over 6NOK to the US dollar and she gave me 570NOK for $100US. I never did see the town's one ATM so if coming in by cruise, I'd recommend getting a little money in the previous ports, Stavanger and Bergen both had a lot of ATMs.