33 nights in Spain: itinerary suggestions

Sounds like a wonderful trip Becky, lucky you! I was in Spain for about 28 days in April/May 2016, and loved it. My itinerary was quite similar, although involved the RS Spain Tour, with a week on my own in Barcelona at the beginning and another week in Andalusia at the end. I won't mention all the major sites, most of which you listed, but will just add a few more unusual ideas:
1. In Barcelona -- (a) I took a 5-hour food tour with Taste Barcelona which was excellent; a combination cultural and food tasting walk through 4 neighborhoods; lots of great food, pricey but worth it; (b) I also took a day tour called "Medieval Villages of Catalunya" which visited the ancient small towns of Besalu, Rupit and Tavernet, which I loved. (c) if you go to Palau Guell, be sure you continue all the way to the roof! Palau Guell was quite dark and unlike other Gaudi buildings. I understand the Guell family got tired of the dark, and next moved to what became Park Guell. I got quite tired walking up the stairs from one floor to another and another, and almost stopped short of the roof. Thank goodness I did not. I asked staff at Palau Guell where nearby they went to eat themselves, and they recommended Tapas Guell (or maybe Guell Tapas) almost directly across the street, just a few doors down, and it was very good.(d) if you enjoy "world cultures" and their art forms, as I do, I really liked the quite-new Museu del Mundo (?), very near the Picasso Museum. It has a limited number of very well-displayed works From each of various traditional cultures from Africa, South Pacific, Himalayas, Asia, etc.
2. Madrid -- Mercado de San Miguel (?) was very interesting, a market now turned into a terrific food court, with various vendors selling very small amounts of diverse foods, many for 1, 2, 3, maybe 5 euros, so you can buy this and that and then sit and enjoy. I was there off-hours, and hear it gets really hectic at prime meal times.
3. Granada -- a high point was having dinner in one of the nice "carmens" overlooking the Alhambra from a distance, as the view of the Alhambra changed from sunset to dusk to nighttime illumination, just marvelous including for low-light photography. I was with a group, not sure if dinner with a view would be possible for just one person, but maybe you could bring your own and find a similar spot to spend a couple of hours at that time.
All for now, enjoy!

Places I especially enjoyed (though I don't know how much slack you will have):

The Sant Pau modernista site in Barcelona. Still very lightly visited, a nice change in Barcelona. It involves some outdoor walking, so pick a non-rainy day.

Girona: quicker to reach than Figueres and a great place for just wandering around, though I really liked the museum (skippable if you do MNAC in Barcelona, I'd say) and the two cathedrals.

The Monasterio de las Descalzas Reales in Madrid. Rick covers this in his book. It's not an easy place to visit. As of May 2016, if you wanted to take an English-language tour, you needed to show up before the place opened (9:45 might be early enough; I don't know) to be first in line so that if they were going to do an English tour that day you had a chance to be on it. There was no advance info available about what days they would have tours. Very catch-as-catch-can. I ended up on a Spanish tour and very much wished I had re-read that section of the guidebook.

Cuenca: If you hadn't already bought your Madrid-Valencia train ticket I'd have recommended a stop here. Worth a full day between the wandering and two good modern-art museums. It's not really practical as a spur-of-the-moment day-trip because of the high cost of last-minute AVE tickets.

Nice slow trip. You'll have a great time with many memorable experiences.

I'll add a few things to your Barcelona time, and do a bit of reorganisation to avoid some duplication/overlap around the Ramblas/Barri Gotic.

Day 1 (Thu)
Arrive Barcelona late afternoon
Staying in the Eixample

Day 2 (Fri)
Montjuic Castle
Miro Foundation
Catalan Art Museum (MNAC)
Magic Fountains

Day 3 (Sat)
Picasso Museum (morning reservation)
El Born walk - Santa Caterina market, Basilica Santa Maria del Mar
Guitar Trio at Palau de Musica Catalana @ 1800

Day 4 (Sun)
Barri Gotic walk - history museum, cathedral at noon for La Sardana dance

Day 5 (Mon)
Sagrada Familia @ 1100
Hospital Sant Pau

Day 31 (Sat)
Arrive Barcelona @ 1400
Las Ramblas walk - La Boqueria, Palau Guell, Port

Day 32 (Sun)
Park Guell @ 1030
Eixample walk - Casa Mila/Casa Batllo

Day 33 (Mon)
Day trip to Sitges

If you are interested in Jewish sights, day trip from Barcelona to Girona to see the medieval Juderia and the excellent Jewish museum, describing Jewish life in the Middle Ages. Allow time in Cordoba to explore its Juderia, one of the best-preserved in Spain, including the Casa de Sefarad museum and the medieval synagogue across from it. There are also synagogue remains in Toledo. There's almost nothing left in Sevilla but there is an excellent private guide I can recommend who has ferreted out the few physical remains and is an expert on the history of the Jews in Spain (not available on Shabbat).

I think a day trip to Jerez is worth it for the horse show. You can also see horse shows in Cordoba at the Royal Stables. I enjoyed both.

In Barcelona, the city hall is open to visitors once a week from about 10 to 1, can't remember if it's Saturday or Sunday. It's free and beautiful.

In Madrid, take your passport to the Naval Museum. '

In Sevilla, there's a new sight, the Palacio de las Dueñas. It only opened about a year ago, so it's not in a lot of guide books yet. Well worth a visit.

Thanks to all for the great ideas. Yes, I feel like a very lucky woman. I am already adding to my plans based on your suggestions.

Very grateful for your willingness to share!