I am 67 years old retired woman, and thinking about going to Amsterdam for a week or so, on my own.

If you would like an upscale spot near Amsterdam Centraal station, the NH Barbizon Palace is very nice. You can get anywhere in Amsterdam on trams from the front of the station. Frequent trains to Den Haag and Delft, plus to Arnhem where you can get a bus to Otterlo and to the Kroller-Mueller Museum.

Sounds delightful, good for you! When are you considering going and are you only traveling to one city? (No musts, just wondered.) I've been to the Netherlands multiple times by myself as a woman and always felt very safe in tourist areas. The Anne Frank museum will sell out fast, I believe it's 3-4 months ahead, (can someone else chime in about booking timing?) Van Gogh & Rijksmuseum also work better with advanced tickets, but when I've looked they've been relatively easier to get. Personally, i like getting to famous museums as close to opening as possible, slightly fewer crowds.

This was a wonderful trip report, to get some ideas going, hope you have a great trip! https://community.ricksteves.com/travel-forum/trip-reports/the-netherlands-belgium-april-2024-brought-the-rain-pants-needed-the-rain-pants

I have just come home from Amsterdam and stayed for the second time in the De Ware Jacob hotel, which is a five-minute walk from the Concertgebouw and the trams that arrive and depart there, and just south of the complex where the Rijksmuseum and Van Gogh museums are. It’s a much quieter part of the city than the rowdy bits nearer to the Centraal Station or around the canals, but you can access them by tram or bus.

Another hotel that is right around the corner there (I’ve not stayed there but a friend has and quite liked it) is the Conscious Hotel Museum Square. The prices there are a little lower than at the De Ware Jacob.

Please note that in general, hotels in Amsterdam are expensive, and only getting more so. One does get sticker shock looking at the rates ! And I don’t believe either hotel includes breakfast in its rates.

(Just to note that the 12 tram runs directly to/from Centraal station to Concertgebouw, no changes needed.)

On Kim's recommendation I stayed at De Ware Jacob in 2023 and really liked my stay there. The room was super comfortable, staff was very nice. I'm not a breakfast eater so didn't have anything but coffee in my room. For me, the location was ideal as my visits are museum heavy and I was seeing the Vermeer exhibition at the Rijksmuseum that year. For context I am a mid-70's solo woman traveler and I liked that this seemed to be an actual neighborhood.

The only caveat is that 1.5 days out of my 4 night stay had the elevator down. I don't mind walking down. Walking up is a pain because it is the typical old Dutch steep and narrow stairs so once I went in I stayed in, lol. The morning I left the housekeeper saw me with my suitcase headed for the stairs, picked it up and ran down with it. She was nimble, lol!!

In spite of the elevator issue I would stay there again.

The Mauritshuis is easy to get to as is Delft. The Kroller-Mueller is more difficult. Last time I looked at their website they had some kind of day tour you could take to visit them which might be a good way to go. I've been there but it was on a Road Scholar tour so I didn't have to plan transportation. It's excellent, the sculpture park is fantastic if the day is fine but the Van Gogh Museum in Amsterdam beats it for the art for my tastes.

I wrote a review of the Nadia, which is affordable.
https://community.ricksteves.com/travel-forum/netherlands-reviews/hotel-nadia-recommendation-with-lots-of-caveats
The "place" I really want to stay is https://sweetshotel.amsterdam, which is less a place than a series of places. Maybe alone you wouldn't feel comfortable, but it's really a very safe city.
Since you are retired, I suggest taking as much time as you possibly can for this trip and, rather than day tripping to The Hague and Delft, consider adding stays in those cities, which are likely more affordable than Amsterdam.
In Amsterdam, I recommend doing an evening canal tour. I am a fan of Those Dam Boat Guys, but others on the Forum prefer Captain Jack.
It's very easy to get around on foot or by tram/bus. You don't have to brave the bike lanes (but do watch out for the bikes--they stop for no one, not even cars!).

Any suggestions regarding the most convenient, safe, and affordable places to stay?

"Affordable" is probably best defined by you. "Safe" is easy - the Netherlands is very safe especially in the places where most tourists will stay. "Convenient" for Amsterdam parts of your trip will be near Vondelpark or the Museumplein where the AF House will be a little bit away. If you're a "walker", you can easily cover all your spots in Amsterdam by foot from somewhere in the Vondelpark/Museumplein areas. But if you're a walker, most of the core of Amsterdam is easy peasy to navigate with proper shoes, a head on a swivel, and time management.

With that list of things to do, I'd suggest you expand the "week or so" a bit UNLESS you're really a busy traveller and/or can trim some items.

While you can combine "big" items into the same day, I generally like one per day, so just hitting museums, you're at the week or so already.

I'd consider splitting the stay to two home bases - Amsterdam (by the museums) and maybe Delft (or the Hague). In Amsterdam for a full week, you get to comfortably hit the museums, concert, and general touring, and then popping out to stay in Delft, you can explore there plus easily go to the Mauritshuis for a day trip, and even rope in other things like Rotterdam, Kinderdijk, Leiden, or the sea.

And the Kröller-Müller Museum will easily be a full day outing from Amsterdam.

Regardless, the Netherlands is a GREAT place to go since it really is an easy to navigate spot for solo or new travelers. Depending upon when you go, there are a lot of other things to see and do as well.

convenient, safe, and affordable

Pick any two.

Hi, I am the same age as you and mostly replying to be an encouragement to you. Yes, go, and have a fantastic time! The last two times I was in that area, I stayed in Leiden which I would recommend for your night before your flight. It was cheaper to stay there, very convenient to the airport, and a nice town.