We are planning to use Malaga as a base for some day trips to Ronda, Granada, and maybe one of the white hill towns. We have 8 days. Any suggestions?
Suggestions in what respect?
Neither do you say by what transport you will do these day trips. If you mean Malaga, the city, it is certainly the public transport hub.
'one of the white hill towns' - Which one of hundreds? There is little to see or do in many after an hour except lunch or drink and many are simply known for the attractive location, their views or view of them from a distance.
We use Malaga as a base for travel in Andalusia. Our preference is to rent an apt close to Malaga.
We rent a car and enjoy daytrips throughout the area. Granada, ronda and a host of places are just at a two hour car ride. We enjoy visiting "destinations", but also getting out to see what we can see. We suggest not trying to park in old town/tourist areas and to pick a nearby residential zone and walk/bus into the tourist areas. This reduces stress of narrow street driving, usually provides more cheaper parking spots and reduces (we believe) opportunity for theft. We do not speak spanish and do venture into a number of non-tourist area without any real communication issues.
Train and bus travel options are easilly available from Malaga and we use them, especially for a trip to Seville (which we do as an overnite).
Malaga offers a relaxing pace and has a terrific pedestrian shopping/restaurant district. If a cruise ship is in port we do stay away until late afternoon when they have reboarded. In Malaga the beaches are "pebbly", but good. We find the marina, old fort, cathedral, old town, museums and walking opportunities to be sufficient to enjoy some relaxing days.
Granada easily warrants staying over a night or two. You should reserve ahead to visit the Alhambra, and the timing of that reservation might affect your choice of whether to sleep in the city. Ronda's easier to see in a daytrip, but that's what many other people are doing too, so staying overnight there lets you see it with fewer crowds.