I agree about Rome - avoid it if possible. I don't agree that you can walk around easily - the pavements are cracked, broken, full of potholes, and extremely narrow. The distances are short-ish, but you can't enjoy the sights as you have to watch where you're stepping. The city has so much to offer but it is all run-down and badly presented. Such a pity.
The South of Spain is perfect. We were there a few years ago in September and it was 44° at 6 pm. An exception, of course, but it should certainly be pleasantly warm. Such a richness of historical sites and culture, Angela's pictures only scratch the surface!
We did a coach tour (the distances can be surprisingly long if you want to fit a lot in. ) DH didn't like the idea of driving, and the coach tour covered exactly the right places, so that suited us fine. We tacked on a week in a holiday resort to recover.