Loire Valley-Car Rental on Sunday from Tours?

Where will you be coming from? It's a long way from Paris for just a day. What do you want to see? What do you consider to be the "sights"?

You need two things, neither of which I think you can obtain: a rental car and more days. You really need a week in the Loire Valley. That's how long we were there and only saw a fraction of the chateaux in the area.

I'm not quibbling, but note for rental agency searches that the TGV stop for Tours is called St. Pierre des Corps. Note that even on weekdays, the agencies close for a two-hour lunch. This appears on major car rental website details for a specific location.

We put off the Loire to our sixth or seventh trip to France. We slept there three nights, with a rental car, which I recommend. We prefer air conditioning in summer, which can be hard to find at a low-priced hotel. I wish we'd had time (and advance purchase) for a Son et Lumiere or a Candlelight Illumination event. (with bug spray.)

I'm not quibbling, but note for rental agency searches that the TGV stop for Tours is called St. Pierre des Corps.

Yes, that's what I found when I checked the Hertz Office in Tours. From the site:
Hours of Operation: Mo-Fr 0800-1200 1400-1800, Sa-Su closed

Hundreds of people a day visit the Loire Valley for one day - Tours is in the commuter belt for Paris these days. It's only an hours from Paris.

Some TGV trains got to Tours, some stop at Saint Pierre des Corps on the way to Poitiers or la Rochelle. On a Sunday the only car hire places open will be at Saint Pierre des Corps, and then probably only in the morning. Even though some of the Tours car hire places say they are open Sunday, usually they are not (and they are not all that close to the station, either)

There are a number of companies that do tours from Paris, and yet more that do tours from Tours. Prices range from about 90euros pp to 300-400pp. You gets what you pays for: the cheapest tours bomb around the loire valley in a minibus and drop you off at the gates of the chateaux for an hour or two, the more expensive ones are private and all inclusive.

Thank you for all of your input. Unfortunately we only have one day. I will look into some of the tour groups Mr. Steves' recommends.

malynda. - don't forget to check out tour companies that aren't in the book. No book is exhaustive, and like most guidebooks the RS book only lists about 10% of what's available.

(It's the reason there is so much angsting about restaurants in Paris - I own dozens of Paris guidebooks, yet in total they list less than 1% of the restaurants in Paris. A visitor might be worried that's all there is. )