Late March - Spain and Montpellier, Nimes FR

It's ok, but you are backtracking and cutting it close going from Aigues Mortes back to Montpellier to catch a train. Driving in Montpellier is a huge pain in the neck and you are in the center of the city.

Instead, you can pack everyone up, check out of the MPL hotel and pick up the car to go to Aigues Mortes. Then, in the evening, instead of driving back to Montpellier, go to Nîmes, turn in the car, and check into a hotel in downtown. You can then spend the next day exploring Nîmes and the museum, and catch the same train, but a half-hour earlier at 17:46 at the Nîmes Centre station. If you were to keep the car the next morning, you might consider visiting the Pont du Gard and maybe even Uzès.

Don't miss the salt marshes, Salines du Midi, next to Aigues Morts.
Why the Halles Castellanes? There's no place to eat inside that market. If you are going to be at the Cathedrale and Botanical Gardens, the rue Jean Jacques Rousseau and the Place de la Canourgue have many restaurants for you to try. If you go to the Saint Roch church, there are a lot of restaurants around there and the best ice cream in Montpellier at La Banquaise ice cream stop.

This is super helpful. Thank you! We are trying to minimize hotel changes....what would be your thoughts on staying in Nimes vs. Montpellier? Or, should we stick with Montpellier and do our Camargue/St Mare de le Mer exploration on a day when we are not checking out and catching a train? We could do Nimes as last day and catch train to BCN in Nimes?

Why are you eating twice at the most tourist centric market in a great food city like Barcelona? There are much better choices. Also I think your day 2 is very busy. Do you know how you are going to do with jet lag? The three places you mention are spread out and you do not leave much time for all of them. Also you do not mention lunch? Won't the 14 year old be hungry?

I’d love any additional food information you may have. We are foodies, so not at all intimidated by eating in a. Foreign city. I didn’t specifically call out lunch in BCN - our plan was to find non tourisry places wherever we are. (And lunch is included with Montserrat ticket)

Do you have the RS Spain book? That is where we got our recs from. We also did a food tour that we highly enjoyed. That might be one to look as they have ones, day and night. We noticed that Spain even more than France or Italy had very specific times that they were open for lunch or dinner. We normally like to do a late lunch and found that problematic many days. We do eat dinner late but after our show at the Palau de la Musica Catalana we found only a few places open late. This was on a Monday about 10:30 a few weeks ago. We asked our hotel and had a nice dinner but we closed the place down at about 11:30. Our show started at I think later than yours so you might not have this problem. .

Enjoy Great city.

"...staying in Nimes vs. Montpellier..."
Since you are looking to do a day trip to Aigues Mortes and what is called "La Petite Camargue" west of the Rhône, yes, stay in Nîmes. You also mentioned Saintes Maries de la Mer, which is even further east than Aigues Mortes and across the Rhône in the Camargue. I doubt you have enough time for everything but you'll see. Saintes Maries de la Mer is near Arles.
To be more efficient with your time, stay in Nímes, do your day trip to Aigues Mortes and more. Then on the 26th, take a morning train to Montpellier Saint Roch station, store your luggage at the station and visit the city which is walkable. Finally, take that evening train to Barcelona from the Montpellier Saint Roch station.

Food: we don't really do breakfast in France and Catalonia, even most of Spain. Lunch is our main meal. But you have a 14 year-old boy, so I suggest you stick with your hotel breakfasts because that is where you'll find the largest bottomless offering: cold cuts, cheeses, eggs, potatoes, fruits, as much as he can eat. Then have a hearty lunch around 1:00 pm and lighter dinner. (I'm still curious where you saw a suggestion to eat in Les Halles Castellanes, which has no dining. Les Halles Lissac has some good stands, though.)

If you are foodies, try "Hungry Onion" online for Barcelona food suggestions, and yes, do a food tour. I've only been to two RS recommended restaurants, but both tried to hit me up for a tip because they serve so many Americans. In Nîmes, I found the restaurant on the top floor of the Romanité Museum quite good, but there are other places.