Itinerary check!!!

1. I recommend you stay in Madrid and take Toledo and Segovia and El Escorial as separate day trips. That is what I did.
2. I think you have enough day trips with Toledo and Segovia and Escorial but see how it goes in Madrid and make the decision to include another when you get there.
3. Listen to your common sense which told you save Sevilla, Granada for a return trip.

I was fortunate to have enough time to stay in both Toledo and Segovia, but in your situation, I'd day-trip from Madrid. (If I had to choose one for an overnight, it would be Toledo.) I haven't been to El Escorial.

I really enjoyed Cuenca, which is on the AVE line between Madrid and Valencia. It's viable as a day-trip if you can snag a promo ticket on the train; otherwise, it would be too costly (for me). I'm not saying that Cuenca is better than Segovia (hard to beat that aqueduct!), but it has a very picturesque Old Town perched on the edge of a ravine, with houses hanging over the precipice, and there are two good, small modern-art museums. The cathedral is also worth a visit.

Definitely do not try to squeeze Andalucía into your itinerary for this trip.

Thank you both for your help!! It's very reassuring to hear that my planning is not out of whack! Will add Cuenca to my list!!!!

I agree with acraven, adding, San Lorenzo del Escorial is worth about a half day between the building itself and the royal crypt. It is worth visiting. Just a few miles up the road is the the Valley of the Fallen; Franco’s monument to honor those who died in the Spanish civil war and built using prisoners’ labor. There is a huge cross topping the monument. If driving from Madrid towards Zamora the cross can be seen from miles away. It is worth a couple hours visit. My guess is there are busses from El Escorial that run frequently. Between the two places you could easily fill a day.

I may be a dissenting voice here by suggesting Barcelona be left for a future trip.
Spain has 2 main gateways for intercontinental flights - Madrid and Barcelona. Visiting Andalusia in the future will most likely involve flying through Madrid again, whereas Barcelona can be reached directly. So my thinking, with your flights booked in/out of Madrid, would be to hop down to Andalusia on this occasion. April is a wonderful time for the south of Spain as well.

It sounds like you have 10 nights on the ground in Spain.

Day
1. Arrive in Madrid (4N)
2. Madrid
3. Day to Toledo
4. Day to Segovia
5. Train/bus to Granada (2N)
6. Visit the Alhambra
7. Train to Seville (3N)
8. Seville
9. Seville
10. Train to Madrid (1N)
(via stop in Cordoba for the Mezquita)
11. Depart from Madrid

I have to agree with the other poster that Andalusia might be better than Barcelona. You picked 2 big cities and while both are great, Seville offers a greater constrast and IMO prettier visit. Also, the Alhambra is a must see. Leave Barcelona for later, it will be quicker and cheaper to come back to Madrid for return flight.

Thank you for the suggestion for Andalusia - will definitely have to ponder that one - only trouble is I really, really want to go to Morocco as well and def won't have time for that... ah, the travelers dilemma - so much to see/do and so little time!!

To me, Andalucia and southern Spain is a trip all by itself. One could spend three weeks there and not see everything.

I agree. I consider this trip as a "taste" - it's going to take multiple trips to see everything I want to see!!