Train vs. Car

I've done a similar trip years ago. No car is needed (and actually it's a nuisance) in any of the big cities you mentioned. All cities are well connected via train and/or bus and it's easier not to have one, also because the historical centers are closed to non residents car traffic. However I would definitely rent a car for just a couple of days (that's what I did) in Andalusia just to visit the countryside and the pueblos blancos (white washed villages), such as Ronda, Arcos and other small towns, such as Nerja. Small villages and countryside are more easily done by car, because bus/train links are not as frequent. Lots of baggage may be an issue however if you are relying on trains. If you have a lot it may be easier to have a car. However you'll have to park it at the hotel while you visit the big cities because you won't be able to use it. That will feel like a waste to rent a car just to keep it in a hotel garage (often for a daily parking fee). All the cities you mentioned have trains, including Ronda. Buses are also an option. When I went I rented a car at the end of my stay in Granada and drove around the countryside and smaller towns of Andalusia (incl. Ronda, Arcos, Nerja, Gibraltar etc.) and returned the car as soon as got to Sevilla, where having a car was a nuisance. Other than that I was relying on trains and public transit.

Thank you.
So....we will have 8 full days in Spain. How would you allocate the days between the cities we want to visit....Madrid, Toledo, Seville, Cordoba, Arcos and Ronda, Granada and ending in Malaga ?

8 days may not be enough for all of those I'm afraid. Madrid: min. 2 full days (at least 2 nights) Toledo: day trip from Madrid (so add at least 1 night in Madrid) Sevilla: min 2 full days (at least 2 nights) Granada: min 1 full day (2 nights)
Ronda+Arcos de la Frontera: one full day as a day trip with a rental car from Sevilla (just rent a car for one day) (therefore add at least a night to Sevilla) Cordoba: you should skip it, not enough time and the places above are nicer. Malaga: I wouldn't spend a minute in it. Just high rise hotels after high rise hotels on a beach that's not even that impressive. Just go to Honolulu and you'll have a nicer Malaga. Go there just in time to board the cruise ship. You could save some time if you rented a car at the end of your Sevilla visit and do a tour by car which includes Ronda, Arcos, maybe Granada, where you spend one or two nights. Then you drive to Malaga where you return the car and board the cruise. 8 days is tight though. If I had to cut something I'd cut Madrid to one full day only. I think Sevilla, Granada and Toledo are more beautiful than the capital (but that's just my opinion). Personally you should make an effort to see those 3 as a priority. There isn't much to see in the pueblos blancos (Arcos, Ronda etc.) but going to Andalusia and not seeing at least one of those white washed villages is like going to Paris and not seeing the Tour Eiffel.

great information !!!
Many, many thanks.