Should I learn French?

Yes, learning languages always has benefits. A few basic greetings and knowing how to say thank you goes a long way.

If you meet people whose english is better than your french they will probably switch to french. But if you plan to leave the beaten path and go where you might encounter people that don't speak any english, stumbling over simple phrases in french will be better than not knowing any french at all.

In my experience, it does help to have at least some basic French. Making the attempt will usually result in a better experience.
Parlez-vous anglais? is helpful before launching into English. A phrase I have found helpful - Mon français n'est pas très bon.

I always practice French the six months before I visit France. I also use Duolingo. My pronunciation is really horrid sometimes and it helps me not to insult their beautiful language. But remember, they will really appreciate you trying to speak their language even if only the basic phrases.

Rather than Duo Lingo which doesn't really prepare you for travel I would find an on line site with phrases in French useful for travel and learn those. You must great people properly before any interaction whether it is a grocery store clerk or waiter, or rando on the street you hope to get directions from. And so all the politeness phrases and basic queries like where the metro, bus or toilet is are helpful. With a dozen appropriate phrases you will be fine. People who interface with tourists usually speak English and you can patch along with your phrases and google translate if you are off the beaten track.

There are many sites where you can learn and imitate the phrases you need.

You are right that basic courtesy phrases are welcome. But note that the idea that, for example, Parisians are rude or hostile to those with zero French is well over ten years out of date.

I will plug Rick Steves phrase book for France here. I did study French on Duolingo for about 9 months before my trip, but I took French in high school and college, so I wasn't a complete beginner. The two resources will complement each other. Some of the common phrases you are likely to use may have more advanced grammar and vocabulary than you will have time to learn on Duolingo, so it's good to have both. Google translate is also your friend, but it's translations are more reliable if you have some grasp of how the language works. Your pronunciation will also be better with some practice. My son, with no prior knowledge of French got along fine just using Youtube, Rick Steves, and a few tips from me. Since we also went to Italy, we learned some Italian too. I had no prior knowledge of Italian but I studied Italian alongside French on Duolingo and used the Rick Steves Italian phrase book. I got along fine. It's a great feeling to make a connection with a storekeeper or barista. You will both leave smiling. I was even able to help other travelers on occasion - a group looking for the police station (some say "carabinieri" not "polizia") and a fellow air traveler who looked dismayed when the barista gave him his coffee in a porcelain mug. OTOH, my husband learned nothing but hello and thank you and also got along fine and made connections with English-speaking Italians and ex-pats.

I’d recommend reading “The Bonjour Effect” by Julie Barlow. She was interviewed on Rick’s radio show a few years ago (maybe 2019). She de-codes French conversation manners and helps North Americans understand why our version of politeness can land as rude in French culture.

Here is the perfect Rick Steves Video for you—Beginning French for Travelers:

https://www.youtube.com/watch?v=qYO7snTI5oY

Look at the offerings at a local community college. I took a French For Travelers class through one of those years ago before a trip to France and it was wonderful. The interaction with other travelers and practicing in person was priceless.

Absolutely. Why just French in particular?

It is certainly worth your time to learn as much of a foreign language culturally and linguistically. Still, it's a matter of what you aim to get from traveling.

I work at a foreign language because I just do not like having to rely on my interlocutor's level of English or his desire to speak it, regardless of the level. If there is no desire on her/his part to speak it, all the better for me when it comes to French and German.

Long ago, I memorized how to say, "Bonjour, je vais massacre votre belle langue". It disarms even the frostiest people and makes them smile. They then seem to be more patient with my horribly accented French.

At a minimum I always recommend people learn how to say hello, please, thank you, good day/evening and where are the toilets.

Thank you all for the fabulous input. I am even more excited to learn key French phrases and the resources you all suggest will be a stellar use of time!

"Bonjour, je vais massacrer votre belle langue".

Ah ah... Excellent!!

It's not just being polite and trying to have a conversation with a person. It helps to know enough of the common words to read signage, or to not constantly be asking what the menu says. The important thing to know is that you have to let them know your limitations first, so they dont just think you're drunk or crazy. It's respectful to not assume everyone speaks perfect, idiotic American English. They might only now a few phrases of your language too. The civility lessons seem to be a lot harder for Americans to learn than the language.

I'll put in a plug for Pimsleur which is an audio-based course which I use for a few months before a trip to a country such as Italy or France. What I like about it is that the phrases they teach you'll have down cold by the time you travel and can easily say things like "I'd like to buy X" or "A table for 2, please". Many libraries carry it on CD. In addition to Pimsleur make sure you've learned the numbers so that you can understand when you hear a total such as at a farmers market.

No matter what you use, with only a few months of practice you won't have learned French and be having free-form conversations. You'll have mastered phrases for simple interactions and perhaps a bit more. The Dept of State FSI estimates 30 weeks of 40 hours/wk to learn French according to https://www.state.gov/foreign-service-institute/foreign-language-training But I encourage you to do it! In Paris you're unlikely to run into a situation as a tourist where someone isn't around who speaks English although they appreciate it when you try to do transactions in French. Provence may be a different story, though. I've been in smaller villages in France and it wasn't uncommon at a small cafe or in a shop to encounter a teenager working there who knew zero English. It was going to be French or pantomine.

Lastly, France is a formal society and you should learn the basic rules. Social convention dictates the very first thing you say to anyone, under virtually any circumstance, is "bonjour". Even if that's practically all the French you've learned. See https://community.ricksteves.com/travel-forum/france/finally-travel-secret-revealed

It's respectful to not assume everyone speaks perfect, idiotic American English.

I know we tend to be a bit self-deprecating here, but I’m going to go out on a limb here and guess that Sam meant “idiomatic American English” and not “idiotic American English”!!! Although we might have some Forum members plumping for the latter !! Hahahahhaha

And as to Fred's question:

Why just French in particular?

The OP noted right off the bat:

I am planning on 2 weeks in France this fall…

Haha! :))
Idiomatic….I hope….

I think it's always worth it to learn a new language and is appreciated by locals as a sign of courtesy and respect. I will note two things to consider- 1) pretty much everyone in Paris who has any job that interacts with tourists speaks excellent English, in my experience- and will often switch to English even if your French is pretty decent (in more rural areas you will find fewer English speakers); 2) it makes sense to learn some phrases, but for questions (like "where is the metro") it's not enough to learn the phrase but also be able to understand the response- which will likely be much more complex! French is one of the trickier languages to understand spoken as many of the sounds are very similar and words and phrases "glide" together with some syllables getting dropped completely. So while I think the effort is worth it for numerous reasons, it's important to also manage your expectations of how much you'll get to use it.

yes I meant idiomatic, but I'm going to let it stand . . .

I second the recommendation for Pimsleur. But be realistic about how much you can actually learn in a half a year. Master the basic polite statements, and a couple ways to ask if they mind if you speak English (some may find it insulting to ask if the do or can speak English).

I would never discourage anyone from learning anything or from undertaking any effort of self improvement. However, unless you really speak French, no one is going to notice your efforts at being able to parrot a few memorized words/phrases. What is very important, and this cannot be overemphasized, is that before you say anything to anyone, you start with hello. It makes no difference if it is Hola, Konnichiwa, or just Hello. All will be understood as the socially mandatory greeting - Bonjour. It sounds simple, but many Anglophones do not do this. Sometimes I still catch myself talking without first saying hello.

Walking into a boutique, it's hello or bonjour. Boarding the bus, you greet the driver with hello. Asking for directions, the first word is hello. Walking into a restaurant - hello, then offer your name, as you will of course, have already reserved.

This greeting is very important, much more so than memorizing any particular word in French.

Adding that Google Lens is really helpful when trying to decipher menus and signs. Learning a few phrases is great but it's a whole other thing, for me at least, to translate what little I've learned into writing, often in a swirly font on the menu. https://lens.google/

I am learning French for my trip to France this fall. In my opinion, knowing a few phrases is not very useful because if the other person doesn't speak English, you will not understand their response. At a minimum, knowing how to say good morning, please, thank you, etc. is usually much appreciated. But if you don't plan on really devoting time to the language learning process, I'm not sure it's worth it to memorize a few phrases.

I haven't found DuoLingo all that useful in language learning (I learned Spanish a few years ago to a high proficiency, started with DuoLingo but gave that up in favor of online lessons). I don't plan on studying French with the same intensity, but a resource that has really been helping me is the audiobook Learn French with Paul Noble. Because he doesn't only give you helpful travel vocabulary, but helps you to understand how French works, and how to build sentences using a variety of common verbs. I have looked around quite a bit, but have not found a better resource.

Walking into a boutique, it's hello or bonjour. Boarding the bus, you greet the driver with hello. Asking for directions, the first word is hello. Walking into a restaurant - hello, then offer your name, as you will of course, have already reserved.

This greeting is very important, much more so than memorizing any particular word in French.

100 percent correct - except do memorize bonjour!

Google translate is EXTREMELY helpful, also. If I have a complicated sentence I talk it into my phone - English to French. Then below the French translation hit the speaker button, hold it near your French local so it can be heard. Voila!