Making the most out of 1 week in Oslo, Norway..

Bergen is great. The best fjord in Norway is Geirangerford. That one might be a bit far for you to travel.
I would stick to Norway.

Are you wanting to go to Sweden for something specific or just to say you've been there?

Where in Norway will you be based? Oslo or somewhere else?

Bergen is more than day trip. Consider doing the Norway in a Nutshell route between Oslo and Bergen via Flåm. Scenic trains, bus and ferry through the beautiful Naeyorfjord. This will take a full day unless you decide to overnight along the route.

Then spend at least a full day in Bergen. Take the funicular up to Mt. Fløyen for the views and a walk, visit the Bryggen, a UNESCO sight.

In Oslo there are several museums including The National Art museum and The Munch Museum. Also in Oslo, you could take the ferry to Bygdøy with several museums including the wonderful Museum of Cultural History.

The Oslo fjord is nice, but won't give you the Wow factor of the Naeyorfjord or the Geirangerfjord.

To be honest, I'd much rather go to Denmark (1st choice) or Sweden (2nd choice). But I'd love to accompany my cousin and her husband to Norway, since it is my first international trip, and they're experienced travelers to Europe.

Maybe I should fly with them to Oslo for 3 days, then train or fly to Copenhagen for 4 days and fly home. Part of me says that I should stay and make the most of just Norway. But I really want to visit elsewhere.

If you don't want to go to Norway, don't. If you travel to Copenhagen on your own at the same time that your cousin is in Norway, at least you'll have the peace of mind that someone is "nearby" if something goes off the rails. Copenhagen is a very manageable city with a variety of sights and activities, plus easy day trips (including to Sweden). English is almost universally spoken. It is, on the other hand, just as expensive as Oslo, so if money is a consideration, you might do better sharing accommodation with your cousin in Norway. On the OTHER other hand, traveling alone, you might be more willing to stay in a hostel, which might make up the difference--and might put you into contact with other solo travelers.
You have loads of time to decide and to plan. Start with Rick's videos (available on his YouTube channel). There are lots of other travel videos on YouTube, as well. There is a lot of information on this site, under "Explore Europe," about what to see in Oslo and Copenhagen. Only you know what appeals to you, so see what's on offer in each place and decide from there.
Who only has one week? You, your cousin, her husband or all of you? If you're able to take some additional time, then yes, your idea to travel with them to Oslo for a few days and then travel to Denmark on your own is a good one. But if you're really limited to a week, including travel time, you can't realistically visit more than one city.
Re: art museums in Oslo, I really like the modern art museum and its building. https://www.afmuseet.no/en/
And I LOVE the sculptures in Vigeland Park. https://vigeland.museum.no/en/vigelandpark
As previously mentioned, there are also the National Museum and the Munch Museum.

You could take the GoNordic Cruise Line overnight ferry from Oslo to Copenhagen, or take a train to Kristiansand then the ferry to
Hirsthals with Fjord Line or Color Line, almost at the top of Denmark, then work your way south through the country.

Color Line also run a ferry from Larvik (closer to Oslo, on an hourly commuter rail route) to Hirsthals.

In December this year Vy trains expect to start a through train from Oslo to Malmo (Sweden)- change there for the short train ride to Copenhagen. The through train ran a 6 week trial this summer but was suspended to allow more engineering work on the Swedish part of the line.
There is talk of another two operators also running trains, which may manage to be Oslo to Copenhagen, but with no start dates.

Vy trains run several trains a day from Oslo to Goteborg making that a viable day trip into Sweden. Buses also run that route.

Bergen is an 8 hour direct train ride from Oslo (longer by bus), or a very long day via the Norway in a Nutshell route. Going direct you can do a day return, with just an hour or so in Bergen, or come back on the overnight sleeper train.

I'm hearing 1) you would like to travel with your cousin because your a nervous traveler and 2) you really want to go to Denmark.

I see from an earlier post you will be flying from Newark. Could you convince your cousin and her husband to fly to Oslo on the SAS flights that connects in Copenhagen? You could all travel to Copenhagen together and go through immigration together. Your cousin would continue on another flight to Oslo and you would stay in Denmark.

If that isn't possible then I suggest either travel with your cousin and spend your week in beautiful Norway provided you don't spend your time regretting not being in Denmark or Sweden OR go to Denmark for the week and use the next year asking questions and learning the and outs of traveling in Denmark.

The thing is, I am a 50+ yr old male. I am accustomed to flying, riding trains, and buses by myself - domestically, numerous times. The only difference is that I've never traveled internationally before - so the language barrier and metro systems make me a little nervous.
Since I do have 1/2 Spanish ancestry, I've even considered flying to Barcelona on the same day my cousin flies to Norway. For some reason, the thought of going to Barcelona doesn't scare me very much and I do know some basic Spanish words and phrases. I'd love to see the Prado museum in Madrid, Barcelona seems friendlier and more manageable. Tell me I shouldn't be afraid to fly to Barcelona by myself, plz.

I won't advise on Barcelona since I've never been there.

But, I will say after spending almost 3 weeks in Norway in 2023, there is absolutely no language barrier in Norway. Everyone, even the 7 year old girl I chatted with in a tiny town on the west coast, spoke perfect English. The information signs at the airport and the train stations were also in both English and Norwegian.

I'm certain you will also have no language difficulties in Denmark.

Everyone we met in Norway and also during our very limited time in Copenhagen were friendly and helpful. You have no reason to feel uncomfortable.

I'm not sure Barcelona is friendlier these days. I was last there in 2018, so I don't know the current situation, but I have seen several posts on the Forum about anti-tourism protests in Barcelona.
It sounds like you're very interested in art, so maybe the place to start is to make a bucket list of art museums you want to visit. Choose the top 2 or 3 that are in cities with direct flights from your home airport (Newark?). Use Skyscanner or GoogleFlights to look for a good deal on an airfare to one of these cities (or a crazy good fare to somewhere else entirely). Buy the ticket and get to work with the guidebooks and other online resources to figure out your accommodation, local transportation, museum pass/reservations, etc.
English is widely spoken across Europe, so don't let language deter you.

Thanks all. The encouragement about English-speaking people in Norway and Denmark is really helpful and reassuring.
I do love art and would be thrilled to see the artwork of Velazquez at the Prado Museum in Madrid. Besides Spanish ancestry, I also have German background. I'm not sure about Munich, but Belgium also seems appealing to me. I definitely want to see/tour at least 1 castle and go for a boat ride on a lake or river.

As regards boat rides you could look at the Telemark Canal in Norway or the Gota Kanal in Sweden. By September the other obvious choice of the Skibladner on Lake Mjosa has closed for the season.

There is a very long list of castles in Denmark here- https://www.visitdenmark.com/explore/attractions-cid3/castles-and-manor-houses-cid16

In Oslo the obvious castle would be Akershus, or maybe a side trip to Trondheim for the Archbishop's Palace.

I recently watched a few travel videos. YouTube TV is great by the way. 2 cities that look very attractive and have nice attractions were Krakow, Poland and Bruges Belgium. Please let me know if you've been to either of these places and/or your thoughts about visiting one of them. Thanks, Greg

I have been to Krakow and Bruges and would choose Krakow for many reasons. For you, it looks like LOT flies directly to/from EWR on Fridays, so your one-week trip is easily done with no transfers (other than between the city center and the airport, which I'm sure is straightforward--I took the train). Loads to see and do there, great food, lots of English speakers, much more affordable than Bruges.

Thanks G3rryCee. One of my reasons for going to Poland is that I actually collect Polish pottery dinner plates- so I'd love to buy 1 or 2 direct from the source.
* Also this is my 1st Europe trip.
* I'm interested in art museums, castles, cathedrals etc, as well as seeing locals.
* To me, Krakow seems more attractive/charming than Wroclaw, for example.
* How was your flight to Krakow? I get nervous during take-off and this is my first transatlantic flight.

My friend collects Polish pottery, too! There was a shop right around the corner from our apartment in Krakow. It's called Kopalnia Ceramiki. The address is Starowislna 43, just south of Josefa Dietla, heading towards Kazimierz. I'm sure there are loads of shops. Our apartment was on Josefa Dietla. We liked staying in that area because it was between the main square and Kazimierz and a short walk to either. Loads of trams and buses within a half block, as well. And a large market close by.

Greg, it sounds like you've moved away from the idea of a Norway trip.

I would suggest you start a new posting if you have future questions on places outside of Norway. Many forum members won't see your new questions on Poland or Belgium or wherever because they think your post is only about Norway.

Good luck with your plans.