Yes, several of us have been to Cadiz. I consider it definitely worth visiting, but with only 2 weeks I wouldn't try to include it. To my mind, priority goes to Seville (4 nights), Cordoba (ideally 3 nights) and Granada (ideally 3 nights). If you go to Malaga, I'd stay for 2 nights. For my pace, that's all you have time for--no Ronda or white villages, which I would choose in preference to Malaga. Cadiz is more historic than Malaga but smaller.
Many folks would trim a night off my suggestions for Seville, Cordoba and Granada, but what I saw on my third day in Seville was at least as interesting to me as the Day 1 sights in Cadiz or Malaga (possibly with the exception of Malaga's Picasso Museum for big fans), and staying an extra day somewhere costs nothing in travel time. Now, if you really need some waterfront time or beach time on each trip, including Cadiz or Malaga is a very reasonable choice. I think trying to squeeze both in on this trip would be a strategic error, but I am definitely not a blitz traveler.
I suspect many people find Malaga more immediately engaging than Cadiz; I thought it had a more festive atmosphere.
If you're thinking about hitting both Cadiz and Malaga, be aware that there is no straight-shot fast-train service between the two. You'll have to head back north at least to Seville (some departures take you all the way up to Cordoba) before changing for Malaga. You will pay for those miles. Bus service may be more direct (I haven't checked), but it seems to be slower.