Southern Spain in fall 2019

One question is how you get between Valencia and, for example, Granada (Cordoba may be easier, I've not checked). You can do this by public transport, but it will be a long journey by rail or coach ("bus").

So perhaps this is one journey where hiring a car ("rental") would be worth considering. It's a long drive too, but makes sense if you break the journey and use it to see some less famous spots along the way. There are two basic routes. The specifics are open for debate, so these are examples only. Option A is you could drive west then drop south, seeing some of La Mancha and staying overnight in Ubeda for example. Option B is to head south first then turn west. You could stop overnight in Murcia, seeing Elche on the way south and Lorca or Guadix on the way west.

I like Gibraltar but the more snooty tourists (or "travellers", natch), are quite sniffy about it (evrn though they've probably never been there!). It's certainly worth visiting, but I think 2 night's stay is unnecessary. Instead one night or a day-trip visit would be sufficient.

People have different views, but I personally wouldn't consider Ronda a must (it's nice and we spent a few days there relaxing and doing little, but there aren't many sights). Cordoba, Malaga and Cadiz would all be higher in my itinerary.

Since you're spending a fair bit of the trip in Andalucia, I think it's worth buying the Rough Guide to Andalusia which is pretty good.

I would consider Córdoba a must see. And would eliminate Gibraltar.

I agree with Suki

Malaga was a 2017 Cultural City and has more going for it than a lot here give it credit for. However, is it better than Granada or Cordoba? Maybe not, but it is still more relevant than many others. It isn't just a beach town for retired Brits. There are excellent museums, Roman ruins, etc.
As must as the Costa del Sol may not be relevant, I enjoyed the bus from Valencia to Barcelona seeing a number of coastal towns with fortresses and castles that looking interesting for short diversions. I am not sure whether Valencia to Malaga offers the same, or not but that might be a car option. I took the fast train from Madrid to Valencia and it was under 2 hours. Also, new train service started up in June for Sevilla to Granada, so there may be new options from Valencia. Just not sure.
I would look at an 'open jaw' flight flying home from either Malaga or Sevilla rather than backtracking to Valencia.
Depending when in November you are traveling, it may not be as 'cool' as you anticipate. I was there late October to Nov 17 and that area was tshirt and light trouser or shorts weather. Often sandals. Use something like wunderground dot com for historical temp and precipitation. Normally November is the start of rainy season, but check out the past 5 years of what has really been happening.
Edit, as you mention RS guide, I assume that you are looking for hotel accommodations, but if you are considering short let apartments, I have a couple to recommend.

I too, would skip Gibraltar and add Cordoba. We had a fabulous stay at Casa del Aljarife in Grandada. https://casadelaljarife.com/en/ . Damian and Rocio were wonderful hosts who can't do enough for their guests; huge room that was immaculate; all of their local restaurant recommendations were spot on. They will purchase your Alhambra tickets for you at an extremely nominal fee, and for us, it was definitely worth the convenience. In Sevilla we had a nice stay at Hotel Amadeus; good location; friendly staff and nice rooftop dining/bar.

I agree with the people who recommend visiting Cordoba, and I recommend spending 2 nights there if possible. I haven't been to Ronda, but based on my research for our 2017 trip, I got the feeling that Ronda is a "second tier" destination because it doesn't have the historical and cultural significance that Seville, Granada, and Cordoba have. Cordoba's history is Roman, Moorish, Christian, and Jewish. It was one of our favorite places. The Mezquita is magnificent, but there is more to Cordoba than the Mezquita. We loved the Alcazar gardens, Palacio de Viana with its 12 patios, wandering the Juderia, and the Roman Bridge at night with the illuminated Mezquita as its backdrop. The Juderia (Jewish quarter) is beautiful with its narrow streets, white-washed buildings, flower filled patios, and small squares.

I definitely recommend 4 nights in Seville, and at least 2 nights in Granada. Seville is a large and architecturally beautiful city with many important sites. The Real Alcazar was one of our favorite sites on our trip, along with the Mezquita and Alhambra. We loved the cathedral, Casa di Pilatos, Plaza de Espagna, Triana, and wandering the Santa Cruz area. Seville is a beautiful city for wandering with its many plazas, fountains, parks, etc.

I haven't been to Gibraltar so can't comment on that, but I agree with Maria about visiting Malaga. We spent 2 nights there and wished we had a 3rd night. We visited the cathedral, the Moorish Alcazaba (just gorgeous with gardens, patios, fountains and outstanding views of the port and Mediterranean), Castillo de Gibralfaro, Picasso Museum, and the Atarazanas market. The old city center (pedestrianized) is beautiful, and we loved walking along the promenade by the port, and having drinks overlooking the port and Mediterranean while watching the sunset.

We were happy with all of our accommodations:

Cordoba - Las Casas de la Juderia
Granada - El Ladron D'Ague
Malaga (if you decide to include it) - Soho Malaga
Seville - Apartamentos Suites Santa Cruz

Hope this helps! You will love Andalucia!

Also want to recommend some travel guide books, in addition to Rough Guide that Nick mentioned. I used Michelin Green Guide and Lonely Planet for Andalucia, and I highly recommend both. I also used Rick's guide to Andalucia, but he does not include Malaga, except for a page on transportation options from Malaga to other places. When planning trips, I always use 2 or 3 guidebooks.

I took a bus from Granada to Valencia thus year. Don't do that. It took over 7 hours, and it wasn't even cheap. Make sure you don't have to travel between Valencia and Andalucia twice. Valencia is a pleasant city (I rank it more or less even with Malaga), but unless you have a special, compelling, reason to go there, it just isn't worth two nearly full travel days (before you do any sightseeing) during a 2-week trip.

I like Ronda but agree that it isn't a must. I would first make sure I had allowed enough time to see Seville, Granada and Cordoba. By the time you add Valencia, I don't think there's going to be time for Ronda. Gibraltar is going to push you over the 2-week barrier if Valencia hasn't already done so.

I peeked at renfe.com for trains to Malaga and found there's a train from Valencia to Cordoba at 8 am that takes 3 hours. That sounds like the best option, since the Mezquita and the Alhambra are my two must-sees in Andalucia.

I'm not sure how you'd work in Gibraltar, it's not really near anything. I will defer to Nick who's been there. I guess I'm one of the snooties, I've never thought it sounded worthwhile using the time that could better be spent seeing more of Spain. If it's high on your priorities, maybe spend time in Cordoba, train to Granada, rent a car to drive through the pueblos blancos via Ronda (2N) to Gibraltar, then drive to Sevilla via Arcos.

You can also do Cordoba as a day trip, which we did from Seville, and personally liked it far more than Toledo. We stayed in Ronda for a couple of nights and wished we'd had at least one more -- the area was our favorite on our trip in May (also with Madrid, San Sebastian, Seville, Granada). It's much more peaceful to get away from the crowds and the views (and sunsets) from the hilltops are stunning. It reminded me a lot of Tuscany or Provence, if you've ever been there, though without the vineyards. If you do add it to your trip, the one thing you might consider is whether to stay in Ronda, which is convenient to have walking access to restaurants, shopping, bars, etc. Or stay out in the country at a smaller hotel or B&B to really unwind -- we stopped at Molino del Santo for lunch and almost wished we'd just stayed there. Around Ronda, you may want to check out Cueva de la Pileta, a series of caves that have stalagmites/tites but have cave drawings that are thousands of years old (one of the oldest is estimated to be 25-35,000 years old).