SF - London - Paris - Marseilles?

That does look like a logical progression and the ideal way of traveling between each place. No need to use a travel agent.

There's nothing about that itinerary that says "travel agent" to me. I assume you know that you can buy a multi-city (open-jaw) flight into London and out of Marseille. I mention this because we've had a few folks show up on the forum who thought they needed to buy two separate one-way tickets. I'd book on the appropriate airline website after researching on kayak or some other website (I use Google Flights).

You'll save a lot of money on the TGV tickets if you buy them early, once you're absolutely certain of the timing. If early-August tickets aren't yet available on the SNCF website, they should be there soon.

Distribution of time among your destinations depends on your interests. Four nights (3-1/2 days) in Paris seems a bit short to me, given its size and riches, but I can understand wanting a balance of big cities and the more rural Provence. If you're not big museum people, your plan will allow a lot of time to explore different neighborhoods in Paris.

Thank you very much for the quick replies! Very reassuring. I cut a day off London and added it to Paris, based on your suggestion.

And you're right that we're trying to balance big-city with countryside. Our boys, 14 and 12, are huge birders, and we're hoping to do some birding around the Camargue and other places Not the best time of year for it, but I'm doing what I can to entice them on a European vacation, which they fear will be all museums and cafes.

If anyone has any birding suggestions around London or Paris and Provence, I'd love to know.

I'm flying into Nice (yeah, I know it's not Marseille) via Amsterdam next Sunday. Two KLM flights but ticketed through Delta. KLM does have a seat-reservation fee, but I think I paid a total of under $30 all the way to Nice, most of the cost being applied to the transatlantic leg.

What works well from Washington, DC, might be hopeless going back to SFO, but maybe check to see what would happen with a return from Nice. You could also look at Montpellier, but I can't imagine that you'd find a decent routing that was less expensive than a return from Marseille.

This bird-watching holiday in the Camargue is in May, but it might give you some ideas for an itinerary and/or species to look out for.

Wow, as others have said, this is a terrific site!

Thank you very much for the caveats on the plane connections, I'll rethink our route and really appreciate the warning about the third-party booking sites. Thank you also for all the birding suggestions, our boys will be thrilled to know that Provence holds more than quaint villages and open-air markets!

One more question: between flying out of Nice or returning the car at Avignon and taking the TGV back to Paris for an overnight at an airport hotel to fly home the next day, which would you choose?

Thanks again!

You mentioned your sons's ages and interests in birds so this suggestion: add a day or two to Paris ( would regrdless) and take a 50 minute train ride to Provins. A very cool medieval town and one of the (many) highlites is a bird of prey show. Just a thiught...a very easy day trip.

Patricia, that is a genius idea!

Wow, this gets better and better, thanks!

Changing the order and ending in Paris makes a lot of sense. In fact, I see we could even fly out nonstop SF to London and home nonstop Paris to SF if we do that. Given the tightened security mentioned above, this sounds worth the premium.

I've marked the Provins bird show, thanks!

I guess there's no predicting the weather, but if anyone has suggestions on staying cooler in Provence in late July, early August, I'd love to know.

A simple suggestion: Do it in opposite order. Fly into Marseille, which will involve changing planes in a gateway city and put you in Marseille in the middle to late afternoon, dead tired and ready for a meal and then bed. Explore Provence, saving a couple of days for Avignon. TGV to Paris. Eurostar to London. Home.
Advantage? To fly home from Marseille, you will have to arise at an uncivilized early hour of the morning, uncivilizing your teens, to make that gateway transfer. Better to do the most complicated itinerary at the start of the trip.
The closest to complete source of itineraries, especially multi-destination, is https://matrix.itasoftware.com/
run by Google for airlines. It doesn't sell tickets but will show you the possible combinations and the airlines which will sell the multi-destination tickets . Make your pick, and go directly to the originating airline's site to use its multi-destination search function.
My guess is that the Delta/Air France-KLM combination, almost one airline across the Atlantic, could be a possibility although I have no experience with their San Francisco service.

I am going to the Basque country this July and booked on Air France. Air France has HOP which is a low cost option. I booked Air France from SFO-CDG leaving at 3:10 PM arrive 10:50 AM the next morning then you can go to Orly Airport via the Les Cars Bus or UBER and I found a Hop R/T flight for $170 to Biarritz and you can also fly to Marseilles. There are also HOP flights from CDG but Orly may be cheaper.

What you may decide to do is fly into Charles De Gaulle then take the Eurostar to London and visit Paris then book a round trip Orly Marseilles Flight (Orly is only 9-12 miles from Paris). Stay in Pairs for a few days before and then a few days after and then fly home from CDG.

Another option is WOW Air via Iceland, Norwegian Air Charter to London(From Oakland). and then you can take the Eurostar to Paris and then fly or take the train to Marseilles and fly back from London on Norwegian Air(You could book a Marseilles -London Flight) stay overnight in London.

WOW Air lets you stay in Iceland on a stopover as sometimes you may need to overnight.

Another airline option is XL Airlines to CDG. Iceland Air is another option.

You can also try flying from Oakland-Barcelona on Fly Level(An Iberia Low Cost Carrier) fly to Marseilles) then a train to Paris stay in Paris, train to London stay in London and Norwegian Air back home.

Hope these are good options.

Have you checked this site?

This account of a family bird-watching trip in late July based on Béziers (Languedoc, not Provence) contains this gem of a quote

We had intended to make a day out of a visit to the Camargue, however,
my contact Francois Guerquin told me and I quote "Of course you could
also target Camargue but I don't advise it, too hot in summer - it is
best in migration and in winter. The only guaranteed species in July
is mosquito", so we took his advice and stayed away.

My advice to stay cooler would be to go higher: maybe into the Cévennes or the area NE of Avignon called Les Baronnies - Rémuzat, for example.

Lots of food for thought, thank you. I'm glad I didn't jump at my first idea for the itinerary.

Thank you for the warning on the Camargue in summer. I was there in April many years ago so am sure I'm underestimating the heat. I was also glad to see from the birding blog post and Rémuzat entry that there still may hope for birding in late July around Provence if we stick to higher places.