Best to Fly to Sevilla or Granada from Barcelona?

Routing sounds good. Some find 2 days in Granada are enough and 5 in Sevilla is not enough. That being said, there is more to see in Granada than just the Alhambra, Cathedral and wander through the Albycin. There is a lot that Rick's books doesn't cover. If first trip to Spain, I might afford more time in Sevilla as that may allow a day trip to Cordoba. Take it from Granada, not Madrid, however. I prefer short let apartments, so cannot recommend hotels.
Is there a reason you wouldn't consider flying to Granada the day of arrival rather than overnighting in Barcelona?
Also, it might not matter, but when are you traveling?

We just came back from our trip. Started in Barcelona. Flew to Granada, bus to Seville and then train to Madrid (just to fly home - I am not a big Madrid fan). I think three nights in Granada would be a lot, but then again, I think four is a lot for Madrid (unless you did a day trip to Toledo).

We stayed here in Granada:
http://www.siloeplaza.com/

and also considered:
http://palaciocabreralillo.com/

and here in Sevilla:
http://www.overlandsuites.com/en/

Highly, highly recommend where we stayed in Sevilla.

The routing sounds very good. As for how many days in each place, look at Rick's Spain book and other books to see what interests you in each place, so you can estimate how long you need there.

Made sure to book your Alhambra reservation as soon as you know your dates! The ideal would be for the day after you are supposed to arrive in Granada, which allows for any glitches (no matter how late your arrival, you won't miss the Alhambra).

I agree with the other posters, 2n in Granda and 4n in Sevilla. Fly Barcelona to Granada. Presently, you have to take a bus from Granda to Seville, but train may be an option whenever you are there. I love Madrid and just returned from my second trip there. There are wonderful museums in Madrid and it is real Spain as are the cities in Andalucia. Barcelona is Catalan, a different culture.
Hotels:
Madrid: The Principal, well located, fresh, new rooms in a vintage building. Quiet rooms although steps from the museums, and El Retiro Park.
Seville: Melia Colon, historic hotel, hreat service, very good included breakfast.
Do you ned a hotel in Barcelona or will you use your ship during your stay there?

Take fast train Sevilla to Madrid.

Great advice, thanks to all. We will plan more time in Sevilla, less in Granada. We will be with friends in Barcelona so touring the city with them at the end of the cruise. We'll be there in October. Thanks for the hotel tips too. This is a great community.

Connie,

Your route sounds great.

Do considered visiting Córdoba from Sevilla or en-route to Madrid.

You'll want to make sure to book your tickets to the Alhambra up to 3 months in advance for best time selection.

You can travel from Granada to Sevilla via train or via ALSA Bus. We took the bus on this route and it was a relaxing ride.

Have a wonderful cruise and enjoy your time in Spain!

It would be easier to fly to Granada then train to Seville and then the fast train to Madrid

Train and direct bus from Granada to Seville take similar amount of time, bus has leather seats, toilet on board and wifi. Half the cost of train, but you can't get up and wander about like on a train. Though Renfe has it down to a fine art, bus doesn't require the transfer of transport mode part way. Bus station is slightly further out in Granada.
In this particular case, there is little difference between the two transports.

Your routing is the best, but I would go 2-4-4.

Day
1. Fly from Barcelona to Granada (2N)
2. Alhambra
3. Train to Seville (4N)
4. Seville
5. Day to visit Cordoba
6. More Seville
7. Train to Madrid (4N)
8. Madrid
9. Day to visit Toledo
10. More Madrid (or day to visit Segovia)

I appreciate the suggestions. Going from Granada to Seville seems like a toss up between bus and train. I see the bus is direct, 3 hours. If we go by train, is it direct or do we have to change trains? Nicer to be able to walk around but having to change trains isn't so great.