I’m seeking to visit Facteur Cheval’s ‘Palais Idéal’ at Hauterives but without a car. Are there any coach tours which visit it? And where from? It sounds rather difficult to visit any other way – I’ve looked at the bus or taxi options from Saint-Vallier-sur-Rhône rail station. Would be grateful for information or suggestions.

According to rome2rio.com the D03 bus runs between the two.

Where did you look for bus options?

The website says how to get there by public transportation, but the last bit is always by taxi.

Practical information - Le Palais Idéal du Facteur Cheval

Kerouac, I think you may be the person who created a beautiful and informative web feature which I’ve seen describing Facteur Cheval’s Palace. If so, I’m hoping you know Hauterives well enough to help me make up my mind whether to seek to stay overnight there. What does the village offer alongside Facteur Cheval’s wonderful Palace? That web feature showed an unusual style to some village buildings. What’s the general atmosphere like? Is there anywhere that you’d recommend staying the night? Are there restaurants?

I didn't stay there overnight, but I did walk through the town which seemed charming, especially with its distinctive architecture. The town does have a hotel or two and some restaurants.
Le Palais Idéal du Facteur Cheval (by kerouac2) | Any Port in a Storm (proboards.com)