There are 7 of us who will be in Santiago in January, before embarking on an Antarctica cruise. On one of the days, we would like to visit Valparaiso, Vina del Mar and the Casablanca valley. Would like help in booking a private vehicle for the day. Any recommendations on how to go about this would be welcome.

You better don't rent a car for that trip. You better go by public bus to Valparaiso and to Vina del Mar.
The reason: driving in Santiago is terrible, and you have to pay a "city-tax" if you drive. But more important: in Valparaiso is a lot of crime. There are warnings about slashed car tyres and broken in cars. Valparaiso splits the tourists: a few love it but much more hate it. We fled after one hour because of all the dirt and run-down-houses/streets. We didn't feel safe. Valparaiso lives of the glory of days gone by. Vina del Mar is nicer, but not much to see there.
I don't know about Casablanca Valley, because we never visit a winery. You can drink good wine allover in Chile. And ofcourse, you cannot drink and drive. But I think there are offered tours from Santiago.
How many days do you have in Santiago?

It’s been a few years since I last visited Valparaiso, but I still loved it! The architecture was so fascinating, and it was a wonderful place to wander through the different barrios. Just a heads-up, there were some serious wildfires there in 2024, and it seems the city is still recovering. Vina del Mar was just another beach town, but we did have some great horse riding in the huge sand dunes nearby. I can’t comment on Valle Casablanca, except to say that if you’ve seen one vineyard, you’ve pretty much seen them all.



When we went, we used public transport and had more than one day. Driving yourself isn’t really an option. I rarely use tours, but this is one example where it would be helpful to have someone else drive and take you to the places you might miss. Check out the tours from Santiago on Google or Tripadvisor.

catch23, yes, this is exactly what I wrote: you either love Valparaiso or hate it. We didn't love it.