Not to complicate matters further, but I have also been looking at east/northeast Paris around Canal St. Martin. Any thoughts as to that area vs. the ones in the 18th?
Possible hotels are Holiday Inn Express Canal Villette at 68 Quai de la Seine (can get a special deal for a spacious room), and the Generator Paris (in one of their spacious twin rooms) at 9-11 Place du Colonel Fabien. To reiterate, a tiny typical Paris hotel room won't work in this case, so it is either two inexpensive singles or a spacious room (215 sq. ft = 20 m^2 or more).

The Holiday Inn Express is currently one of the best locations in Paris if you like a young adult oriented atmosphere.

Note: It shares a building with the St. Christopher's Inn hostel.

Are you looking at all at transportation options in your hotel search? They differ. The metro at the Generator is not direct to the central and involves changes although the bus #75 is direct to Paris central. The metro for the Holiday Inn Express, Crimee, is seen as "iffy" at night by some. There is no convenient bus option. Otherwise both are in areas with a lot to offer.

Iffy? Really? I lived at metro Crimée for 12 years and never saw anything out of the ordinary there. Perhaps you have some specific incidents to report, Envierges?

The Holiday Inn Express is once again right on bus line 60, well 2 blocks from it...

Read carefully. I didn't say I had a problem or had experienced incidents but that "some" feel queasy at night according to what I've read in Paris papers and what some of my single female friends traveling alone at night have said. Maybe a single man notices different things. I was referring to direct to central buses. The #54 is also available but I didn't mention that as it doesn't go to Paris central. Considering what poster said in post 5, I felt it fair to mention what might possibly be a concern. I could also have mentioned that a stay along the Canal might not be as enticing in March as it would be in the summer months.

One of the nice things about forums is getting different views and the recognition that there isn't just one answer or one correct opinion.

One could also wish that posters would learn to be a little bit more tolerant and respectful of another poster's opinion or view. We don't all see with the same eyes.

Hence my comment about Chateau rouge being a no-go zone, having read somewhere that a man can't judge, since they have no boobs. I do go sometimes with women and I do see women who seem not to be bothered.

Generator is a hostel. My last experience was at the abovementioned Christopher's at Crimée - rooms with no WC - one or more per floor to be shared. I'm too old for this, might work for others but do pay attention.
The location was just great - along the canal, quiet, nice with restuarnts and bars. A very nice place to be, imo.

That is very helpful info about the transport, and I'll keep that in mind for sure.

The hostel option I'm considering is at the Generator for a room that is 20 m^2, with a private bathroom. So no "real" hostel experience this time around.

Re the Generator: the bus #75 passes some of Paris' architectural landmarks. Close to the hostel is the magnificent Hopital St.-Louis built as a plague hospital about the same time the Place des Vosges was constructed, hence the similar architecture. Right across the circle from the Generator is the Communist Party headquarters done by Oscar Niemeyer who also did Brasilia. If you can get into the building, it's well worth a visit.

The location of the Generator is quite pleasant -- a vibrant and mixed working class neighbourhood near the Canal Saint Martin. Plenty of cafés and restaurants just a step away and not a single tourist trap. The only disappointment might be finding out the prices of things in the center of the city after being at Place du Colonel Fabien.

I've definitely noticed the difference in prices in and out of the tourist center!

Slightly related:
https://www.nytimes.com/2018/10/22/t...s-on-foot.html

The #75 bus from the Generator will take you right to Nouvel's Philharmonie. Thanks for the link.

Still haven't made a final decision on this. There is actually a stay at both the beginning and end of the trip, so I quite likely will choose two options. But two more hotels I've found a good deal for are Hotel Carlton's at 55 Boulevard de Rochechouart, and Eden Opéra Paris Hôtel at 35 Rue Jean-Baptiste Pigalle. Any thoughts on those?

Location of Eden is nice. Not too close from Pigalle itself. Rochechouart 55 was called Qualys Montmartre when I stayed there in 2015. I quite disliked that hotel : small chambers and yes, the hotel is between 2 sexshops of course. It was noted a 4 stars, something I didn't understand. I don't suppose the rooms would have been enlarged when bought by the Carlton nor that the sexshops moved.

Boulevard de Rochechouart is not considered to be a desirable location by many (although it would not bother me). It is the home of 3 or 4 or the prime rock concert venues in the city (La Cigale, Le Trianon, La Boule Noire and les Trois Baudets), and it has all of the trendy cafés and bars that go with it.

Never enough time
 

I ended up going with a different friend who is a fluent French speaker.
We stayed in two different hotels, Hotel Carlton's Montmartre at the beginning and Villa Pantheon at the end. For both, I found deals that were about $97 USD (including tax) per night, and Carlton's included breakfast. Both are marked as 4* hotels.
We loved both neighborhoods. We never saw anything seedy around Carlton's.
Both hotels had compact rooms, but I know they were a good size "for Paris". Carlton's is refurbishing, but we had an older decor room, which was fine. Villa Pantheon has an eccentric Scottish decor, but it was very pleasant.
Will be glad to explore more options in the future. We did need as much space as we had, so I do advise friends who need twin beds pay close attention to room size.