We will be visiting Cordoba from Seville for a day trip in May. Is a private car/tour for the day beneficial or can we take the fast train and do a walking tour on our own easily enough?
Purely personal decision. A private tour does all the research for you, so if you don't have the time or inclination to research, then let them take you out for the day. If you are interested in research and budget conscious, then do a DYI. You can go with a guide in the Mesquita, or do a guided walking tour. If interested, Global Greeters works in Cordoba so you can take a walk with them. They are not professional guides, but if you want a couple or three hours meeting and walking with a local, that might be a consideration.
Personally I think you can do it on your own. We did it easily. However, organized tours do provide some advantages in prior arrangements but locks you into a fixed schedule. If you are comfortable traveling on your own, you can do it.
Do you know anything about an evening tour?
We have a private tour scheduled in our itinerary with complete flexibility. Don’t want to say budget is not an issue as it would be nice to save where we can, but if we’ll benefit, we’re willing to spend. I’m willing to do my research, but I know from visiting other cities with private guides, there are advantages. So I guess that’s what my real question.
Doing it yourself is easy, so if your main concern is ease of logistics - no need to worry about that. Of course, a guide can always provide information and assistance that is harder to do on your own. I personally prefer to do things myself and rarely hire a guide because I find that for me doing the reading and navigating myself provides a more memorable experience. That's just down to learning style and personal preference.
For Cordoba if you were to do it yourself - the train station is a moderate walk from the old town, or an easy cab ride. Then you can follow a self-guided walk (I think Rick Steves has one?) and go to the Mesquita or other sights of interest. Guidebooks will have information about the site and it's easy to navigate.
Thank you!