We are picking up a rental car in Seville and driving to Arcos de la Frontera, Tarifia, Ronda...onto Nerja and then Granada. How are the roads? Any helpful hints?
My only comment is hopefully you are renting your car OUT of the center of Seville. We had a terrible time attempting to drive to our hotel. We parked the car at a car park on the outskirts and left it there for 3 days. Picking it back up and then driving to Ronda and Granada was pretty easy. Ronda was very straightforward and an easy stop for us on our way to Granada. We did book a hotel in Granada that was near the Alhambra, so did not have to drive into the center of that city and except for the usual difficulty in finding a small B&B (road names/directions not quite perfect...), it was pretty easy.
We drove from the Seville airport to Ronda, plus various side trips. We really enjoyed the driving, although there are roads that seem equal on the map, yet one is very backroad and the other is more primary. Either way, give yourself enough time to catch planes, etc.
Roads are no big deal. They're in good shape and we didn't see much traffic. Avoid the toll roads, AP or autopistas. You save no time vs. an A (or autovia route) and only lose a little time using an N (or nacional route), which slows down through towns. A GPS is always a good idea but keep a general road map handy as a backup. Since you are in Andalucia, you can pick up free city maps of all your stops at the "regional" tourist information center (rather than the local TI) in Seville. Along your route, I'd suggest Jerez as a good stop. We toured two Bodegas there and were glad we did. Near Ronda is Antequera that has some great stone age tombs. I'm not a fan of the Costa del Sol, it's too touristy for my blood, a good alternative is the Costa de la Luz (Tariffa is at one end ). From Arcos and Jerez you could head toward the coast (La Barrosa beach near Chiclana is nice and has lodging choices from resorts to condos to budget hotels) then down toward Tarifa. Along the way you can check out the Roman ruins at Baello Claudia. Near Tarifa, we stayed at Hotel La Torre. It was about five miles outside of town - a nice place and good value. I also think a half-day or so at Gibraltar between Tarifa and Ronda is time well spent. We were there in April. I put a trip report here if you want to check it out.
When you arrive in Arcos find a parking lot or space at the bottom of the hill. There is very limited parking at the top and the streets are extremely narrow in some spots. Instead take a taxi to the top to see the view, and walk back down. There are a few restaurants at the top but you will pay for the location but not necessarily a view; there are a number of others offering more affordable Menu del Dia on the walk down the hill.
Get the smallest car you are comfortable with, especially for Arcos and Ronda. In Arcos you'll have to fold the mirrors in while driving anyway! Of course it's a matter of taste, but I thought our daytrip (hours on excellent roads but caught behind tractor-trailers) from Ronda to Gibraltar wasn't worth it. Since you didn't mention Gibraltar in the OP, don't be tempted to add it. Of course we didn't drive in Seville, but the underground parking didn't seem so bad. If you have time and possession of the car, consider nearby Carmona and the Roman city of Italica. Carmona is sweet in a different way than Arcos. Have you read Rick on the Pileta Cave near Arcos? (We went several years ago, so you need current info ...). Try to spend the night in one of these places - it's true that they're different after the crowds depart and locals come out for a walk and dinner.
In big cities like Seville, be aware that if are turning right, a green light across from you in the intersection only lets you edge forward to wait to make your right turn. The light at your immediate right, as you edge around the corner, wills still be red. You can't go until that one turns green. It makes no sense, but that's the way it works -- try to watch the behavior of local drivers before you drive yourself and you will see what I mean. I don't know what they'd do if two cars wanted to turn right-- guess the second one would have to wait for the next light. The roads are fine, the hard part is always picking up and dropping off the car.