How Many Days in each Place?

You can do it all by train, except for Ronda. Trains are clean and quick. We drove Sevilla to Ronda to Granada, which gives the option of stopping at other white towns along the way. Each change in location takes half a day (except Toledo to Madrid which is 30 minutes) so subtract that from what you plan to see/experience. We did much the same trip mostly by train except we returned to Madrid via Cordoba and did not try for Barcelona. We still ran out of time over 12 days to see as much as we wanted. Three nights per stop IMHO is best to actually have time to enjoy architecture/churches/art/markets/food where you are. There is simply too much to see. Have fun. Plan to come back.

You're covering a lot of ground and too many 1 night stays for me.
I would day trip to Toledo from Madrid
You have to go back to Madrid to catch train to Seville anyway.

Take the bus from Seville to Ronda- it is much quicker than the train.

You are missing our favorite town- Cordoba. We liked it a lot better than Granada.
Most would say add a night to Seville and a night to Granada. I would actually add the 2 nights and spend them in Cordoba.

Consider dropping Barcelona and spending all your time in Andalucia.

What will the weather be like?
I'd assume it will be hot.

I would add two nights to Cordoba. It's a wonderful small city; it's so pretty with its white-washed walls, narrow lanes, patios and flowers. And of course, you have the magnificent Mezquita. And the Alcazar gardens, Roman Bridge, Palacio de Viana with its 12 patios, and more.

Four nights is not a lot for Barcelona, and only gives you 3 full days. I would skip the day trips and spend all 3 days in Barcelona.

Or, as someone else suggests, skip Barcelona for this trip, and make your trip all about Madrid, Toledo, and Andalucia. Perhaps you could fly into Madrid and home from Seville. If that's too expensive, fly into and out of Madrid. A possible itinerary, if you skip Barcelona, could be:
Madrid - 4 nights
Toledo - 1 or 2 nights
Cordoba - 2 nights
Granada - 2 nights
Ronda - 1 night
Seville - 4 nights
And the final night in Madrid if you are flying home from Madrid

It seems to me like a good plan for seeing major sights, but wouldn’t leave a lot of time to slow down and see/appreciate local life.

I’ve taken to saying that you’re doing Spain wring if you aren’t spending a couple of hours a day sitting with a coffee/wine/beer/vermouth.

How many nights will you be in Spain (ES)? Are you flying into Madrid and out of Barcelona? Arrival day is jet lag day so don’t plan on doing anything other than settling into where you’re staying, getting acquainted with your neighborhood and ending the day with a nice meal.
In Madrid there are three museums worth seeing: the Royal Palace, Prado Museum and Picasso’s Guernica at Centro de Arte Reina Sofía. You could easily spend a full day at the Prado and there is a café on the ground floor.
What’s nice is you’ll be in Madrid on a Sat night when it is at its loudest and I am not kidding. You need a minimum of three nights in Madrid and if you take a day trip to Toledo which I recommend vs. sleeping in a town that shuts down when the day trippers leave, stay in Madrid four nights. Logistics wise it will be easier because you must go back to Madrid and change trains to get to Sevilla.
You want to buy tickets for the Alhambra, Picasso’s Museum in Barcelona and the Sagrada Familia before leaving home. Your itinerary looks good. Here is ESs train website: https://www.renfe.com/es/en if you don’t already know about it.

I think you're short on time in Madrid, Seville and maybe Toledo (lots of architectural interest there). And I think your time allocations for Granada and Barcelona are at the minimum. Barcelona's definitely below the minimum if you are going to Montserrat and Sitges. I agree that the omission of Coroba is unfortunate.

Basically, I think you're trying to cover too much ground too quickly. I'd definitely add 1 night to Seville. I'd throw the other extra night to Barcelona because of the side trips you want to take. However, I think the suggestion to leave Barcelona for a later trip is a good one. That would make for a more relaxing visit to Madrid and Andalucia (possibly including Cordoba).

First, thanks for the thoughtful suggestions! I clearly underestimated the wonder of Spain! Based on your comments, I am adding a 3rd week. So, please tell me if I am getting closer to the ideal - then we can linger over "coffee/wine/beer/vermouth" and people watch!!

Madrid - 4 nights? (with day trip to Toledo)
Train to
Sevilla - 4 nights (bus for daytrip to Ronda or should we spend 1 night there?)

Bus or train or car? to
Cordoba - 2 nights

Granada - 3 nights?

Fly or train? to
Barcelona - 5 or 6 nights?

Where should I add or substract?

I will reserve as suggested by Alhambra, Picasso's museum and Sagrada Familia from home. Do I need to reserve train tickets before I leave? I have read the renfe is problematic. MANY THANKS

Looks much better
We spent 2 nights in Ronda and enjoyed it very much
It was a nice break from the busy touristy stuff in the other big cities

Yes, a much better itinerary. So happy that you can add an extra week.

I would use the trains or ALSA bus to travel to most places. I can't make a suggestion for Ronda since we didn't go there. You should check the flight schedules and train schedules to decide which is better from Granada to Barcelona.

When we visited Madrid, Toledo and Andalucia in September 2017, I made all of our bus and train reservations before we left home. I just feel more comfortable and confident doing that in advance. The ALSA bus site was easy to use; for trains, at the time I used a different company than Renfe that I am quite sure has now merged with another company. I forgot the original company's name and who they merged with.

I would not rent a car. Driving into and out of these cities will be very stressful. Train or bus is the way to go.

You do not need a car in ES. This is one country where you can rely on public transportation without the hassle of getting from one place to the next. Trains and busses are clean too.
Take a direct train from Sevilla-Santa Justa to Cordoba-Central (1h). There’s a direct train from Cordoba-Central station to Ronda departing late afternoon (2h). Do not make Ronda a day trip. As a matter of fact, if you can spend two nights in Ronda that would allow you to take a break from sight-seeing and do laundry, etc.
To get from Ronda to Granada requires a change (2h 30m). I suggest flying from Granada to Barcelona.

Friday to Monday Madrid 4 nights

Tuesday to Friday Sevilla 4 nights

Saturday to Monday Cordoba 3 nights

Tuesday to Wednesday Ronda 2 nights

Thursday to Saturday Granada 3 nights

Sunday to Thursday Barcelona 5 nights should I move one of these nights to another place such as Granada or Cordoba? I do plan on day trips from Barcelona.

Should I go from Madrid to Cordoba, then on to Sevilla? Will Cordoba be too quiet if we include it on Sunday? What are the easiest train routes between these locations? I do think I may try to fly from Granada to Barcelona...? Thank you!

I would not eliminate any nights from Barcelona, which is a large and busy city with lots of interesting sites. In fact , you may need to reserve tickets for some of the popular gaudi sites in advance. You have enough nights for Seville, cordoba and Granada. Barcelona is much larger than any of these smaller cities.

I agree with kmkwoo and wouldn't alter the time allocations.

Places you need to have tickets for before arriving at the sight because the ticket lines can well be an hour long or longer (or they could be sold out for the day if you don't arrive in the morning):

Granada: Alhambra (sometimes sells out way, way in advance). This is a very, very tough ticket if you don't plan way ahead.

Barcelona: La Sagrada Familia, Parc Guell, Casa Mila/La Pedrera, Casa Batllo, Picasso Museum, Palau de la Musica Catalana (English tours of the Palau can fill up).

Seville: Alcazar, Cathedral. (Rick's guidebook has a ticketing tip for the cathedral.)

In Madrid some folks recommend buying tickets for the Palacio Real in advance and perhaps the Prado. I didn't see lines of any significance there in May 2016, but that was a long time ago.

The Monastery of Las Descalzas Reales is a very interesting place (probably still covered in Rick's guide, though I haven't seen a recent edition). It used to be very difficult to get an English tour there as an independent visitor. They've fairly recently started selling tickets to those tours in advance.

Tickets for the Monastery of Las Descalzas Reales

Both train tickets (especially) and bus tickets may be cheaper if purchased well in advance, and sellouts (especially of the fast trains) are not uncommon at all if you wait until shortly before the travel date to look for tickets. You have to weigh those warnings against the risk of committing in advance to a specific departure date and time. Take a look at the cancellation/refund rules before you buy.

2 small thoughts:

• try to go see a concert at the Palau in Barcelona rather than take the tour (or maybe do both).
  
  There's something on almost every night. But see something in the main hall, not the Petit Palau.

• the Prado is free in the evenings from 7-9pm, or something like that (as is the Reina Sofia). You
  have to queue, but it moves pretty quickly. If, for instance, all you wanted to see at the Reina Sofia
  was Guernica, the free night option would take care of that.

Thank you for the additional feedback on timing and reservations. Should I add 2 nights in Rondo between Seville and Granda?

Should I go from Madrid to Cordoba, then on to Sevilla?

That might work better. There are no direct trains from Sevilla to Ronda but there is a direct bus (2h 15m). There is a direct train from Córdoba to Ronda but it departs late afternoon.

Thank you Mary Pat! very helpful