My 17-yr-old daughter is travelling to Spain & Paris

For the Paris hostel question, check out the MIJE hostels in the Marais. I think there are more than one. A problem she may find is that many hostels don't allow 17-year-olds, but MIJE does. There may be others, but sure you folks are reading the fine print before you pay for a bed she may not be able to use. On my last trip almost all of the hostels checked my ID for any number of reasons, so no, she can't fake being 18, which is the more typical lower age limit. I have not stayed at MIJE, but I met some hostel roommates who had and they were positive about it. For hostels in general, the only source I would really trust too much is hostelworld.com, where the reviews point out the good, bad, and just plain ugly.

On the transportation question, the very reliable company Flixbus takes less than 5.5 hours, none of them overnight, to Bordeaux. That looks like a good start, but I didn't research the onward journey in France.

Flixbus have a direct daytime bus at 0430, and another at 0900 which is a change at Bordeaux of about 2 hours- arriving at 2005 on 19 July.
The 0430 bus started at Lisbon at 1520 the previous day and continues to Zurich.

Our daughter stayed at Le Village Montmartre in 2024 less than a week before the Paris Olympics. She was 24 at the time, had a wonderful stay and has recommended it to others; however, I am not sure if there is an age limit…

I went to the rooftop bar at a hostel in Paris near the Canal de Saint Martin "Generator Hostel" and it looked like a cool place. The bar was definitely a nice view of the city.

Not a pleasant topic, but you may want to familiarize her with potential issues single young females traveling on their own might face and things to keep in mind.

Many restrooms in bars, restaurants, airports, bus stations, etc., have signs or stickers reminding people that trafficking exists.

Presumably you have already seen this?

https://europa.eu/youreurope/citizens/travel/entry-exit/travel-documents-minors/index_en.htm

Presumably you have already seen this?

https://europa.eu/youreurope/citizens/travel/entry-exit/travel-documents-minors/index_en.htm

I didn't read it extensively, but did see it notes, each country has its own rules

I am having trouble finding a good train route and it also seems very expensive.

I can't believe I did a similar trip at her age with only my Lonely Planet!? For some reason, it seems more complicated as a parent.

What part has she had in the planning? I'd dump 95% of it in her lap, and then review it when she was done. Her intimately knowing the "why" for each decision, plus the various other options considered and discarded, will make her much more capable on her own and agile when she needs to adapt - to a missed bus, a hostel that didn't work out, or other travel challenges - and OPPORTUNITIES.

If you did it at her age with far less resources, maybe she can do it too?

Totally agree with Tom R. If she wants to be treated like an adult, then she needs to start acting like one. Let her do 95% of the planning, put together a realistic itinerary and budget, and then run it by you for a sanity check. That's actually a great exercise in responsibility, practicality, and learning that every decision has trade-offs.

And honestly, that opens up a whole other conversation about the very different parenting styles on each side of the Atlantic 😄. From a European perspective, we tend to give kids a bit more freedom earlier on, but with that freedom comes responsibility and accountability. The idea isn't to remove obstacles for them; it's to gradually let them deal with real-world constraints and consequences. Planning a trip is a pretty good example of that. Better to learn those lessons while organizing a vacation than when the stakes are much higher later in life. 😉

Hello and thanks to all that replied and for the useful links and advice.
Bus is booked and the hotel in Paris (at least as Plan A), highly recommended by a friend. Here is the link if anyone is interested: https://www.solarhotel.fr/fr/
Regarding who should be doing the planning, I very much agree with the comments, in an ideal world. Our world is not ideal right now and it's been a very rough year for my daughter... I'm proud of her for finding the surf camp and she'll take over as soon as exams are done :).