We’ll be there for 3 nights in mid/late September. Aside from the Ile des Machines, what other recommendations do you have?
We enjoyed the Jules Verne museum so much that I came home and reread The Mysterious Island. He was born there. It's a small museum but very informative if you like this author.
Musee Jules Verne, 3 rue de l'Hermitage, 44100 Nantes.
www.julesverne.nantesmetropole.fr
Hi A trip to the coast by train. Pornic, le Croisic or st Nazaire.
The local castle is free and worth half an hour.
There are villages nearby worth a visit. Oudon, Clisson, Trentemoult -- Clisson is IMHO the most interesting.
Le Grand Elephant is a must. Les machines-nantes.fr
For me personally, the most important thing to see in Nantes was the Memorial to the Abolition of Slavery. As I lived in Alabama for 10 years, this was very meaningful; I actually cried aloud when I read and listened to the exhibits. As Nantes was a major slave transshipment and trading port, it's very significant.
The Château des ducs de Bretagne is also a fun visit. And the children's carousel near the Machines is very elaborate and fun to watch.