2 weeks Spain Madrid to Barcelona

With 13 nights here’s what I suggest:
Three nights in Madrid. If you add a day trip to Toledo, make it four.
Two nights in Sevilla.
Two nights in Ronda. You can take a direct train from Sevilla to Córdoba and store your luggage at the bus station that’s opposite the train station and tour Alhambra. From Córdoba take a direct train to Ronda.
Two nights in Granada.
Three nights in Barcelona.

I would reconsider your stance on art if you are visiting Madrid; even the most casual of art fans would be affected by the powerful Guernica at Museo Nacional Centro de Arte Reina Sofía, it right next to Atocha train station which you will probably be traveling from. For that matter, one of the greatest museums in the world is also short walk away; the Prado contains the rich legacy of Spain's greatest artists, it would be a shame to be so close and miss this amazing collection. And I'm just a guy, no art aficionado.

We are absolutely okay with some art. Just tossed it out there so it wasn’t the main focus as I know that’s what Madrid is known for. I also appreciate the above itinerary however I think we are going to skip that region on this trip. Definitely open to suggestions if the places mentioned in my OG post aren’t a must but want to try to minimize skipping around too much and soak in the places we visit. We typically spend more time however this is our first trip after having our little one - he’s not coming - so it’s also our shortest. Appreciate the help and feedback.

I've never been to Tarragona; I don't have much interest in Roman ruins. I'd say Sitges is a more minor destination than the others. It would probably be livelier on a weekend. It could be a last-minute decision, based on how much time you find you need in Barcelona.

There's tons to see in Barcelona, so you may have trouble tearing yourself away. An unusual number of the top sights in Barcelona have such long ticket lines that you really need to buy entry tickets ahead of time. Those entry tickets are usually timed, so you can't just blast through the city, cramming a lot of sights into each day, unless you are either perfect at predicting how much time you're going to need at each sight or willing to leave some of those rather expensive sights early to be sure you're not late for your entry time at the next place.

I'd rank Toledo higher than Valencia and Girona, but all are worth visiting and would benefit from more than one day of sightseeing time.

I'd suggest adding Zaragoza to your list of potential stops. It's right on the rail line between Madrid and Barcelona and has some very attractive architecture, including a Moorish palace now restored and used as a government building. Seeing that would be great since you don't plan to go to Andalucia on this trip. A couple of nights in Zaragoza would be good, I think. It can be very hot in Zaragoza in mid-summer, but with luck you'll be early enough not to perish from the heat.

If you decide to head from Madrid to Valencia, the train will stop at the Cuenca-Fernando Zobel station, which is just outside the town. Cuenca has an atmospheric medieval district on a hill and a couple of small modern-art museums of interest. There's bus service from the train station into town, but I don't know their frequency. A taxi might be both practical and affordable.

Like the fast trains on the Madrid-Zaragoza-Barcelona line, those from Madrid to Cuenca and on to Valencia can be very expensive if tickets aren't purchased well in advance.

If you wanted to include both Valencia and Zaragoza, you'd not have the option of an express train, linking the two, but there is rail service. That slower line runs through another attractive--and very rarely visited--town, Teruel. Alternatively, there's faster rail service from Valencia to Barcelona. I'd recommend taking a look at travel times on https://www.renfe.com/es/en. I really like all the places I've mentioned, but it doesn't make sense to move around so much that you're spending a significant part of your total available time sitting on trains. I would definitely not recommend going to all the places I've mentioned; I'm just laying out some options for you.