In the Loire Valley, are there any "arty" caves that can be visited?

I think you're "onto" something with your question, but the most interesting caves (to most connoisseurs) are a bit further south, in the Dordogne region in France, south and east of Bordeaux. These are appealing from both an art and archeological perspective because there are cave paintings done by prehistoric man.

The most famous of the caves in question is the Lascaux.

This is in contrast to the central Loire, which cuts west across France to Nantes. But some of the southernmost tributaries of the river approach the region of greatest interest.

There are a number of caves in the Loire Valley which have sculpted walls, as well as caves which serve as artists' studios. The Hélice Terrestre, which you mention, is superb, and Philip Cormand's sculptures in Bouvet-Ladubay, are, as you say, great. You can see considerably more of Cormand’s work in the nearby Pierre et Lumière, where he sculpted miniature versions of a number of Loire Valley monuments and bas-reliefs of whole villages.

For another winery with sculpted scenes on its walls, though of a completely different style, take a look at Les Caves Rupestres at the Vouvray winery Domaine Bourillon Dorléans. Some of the bas-reliefs were made by the local sculptor Zaeli, who has a cave studio in the adjoining village of Rochecorbon.

The caves of the Loire Valley, which usually started as tuffeau extraction quarries, are hard to compare to the natural caves of the Dordogne. They have their own charm, much of it owing to the new uses to which the Loire caves have been put.

I've identified 10 sculpted caves plus 14 artists' studios or sales rooms (and much more) located in Loire Valley caves in my eBook "Deep in the Heart of France: A Guide to the Loire Valley's Contemporary Caves", available at www.smashwords.com/books/view/148646. Enjoy!