Thermal spas in France

I find France is a complicated place for those facilities...
Many places are still geared to the "health/medical" clientele with many "teatments" and don't cater well to the "wellness/relaxation" market. Facilities in old, traditional thermal spas can be old, too, hence the mixed reviews.
This said, some places have invested in facilities more geared towards casual "wellness", though, I know of several in the Alps (St Gervais, Aix les Bains, Le Monetier). And the eastern Pyrenees have several scenic outdoor spas in beautiful surroundings, such as Thermes de Llo.

Last summer I considered trying the Thermopolis north of Metz, near Walygator park on the way to Luxembourg. We visit many different German Thermae but had never visited a French one. I'll probably be more at home in a German one of any level.

I've never been yet - my wife had a fall and she wouldn't have gone in until she healed so we changed the holiday away from spas and hope to do that again next year.

I do note that for men only speedos are allowed in the pool area, in keeping with French tradition.

https://polethermalamneville.com/thermapolis/

O'Balia spa thermal in Balruc-les-Bains. This is in the outhwest department of the Hérault.

All the thermal spas are in the alps, massif central or east of France e.g. Vosges. Most are under the name "thermes" or "thalasso" in French. Check out https://www.france.fr/fr/bretagne/liste/les-meilleures-cures-thermales-et-thalasso-de-france