Hi Tideway, unfortunately your quesiton is a bit like asking how long is a piece of string. There is just so much to do in any European country, you really need to have a good idea of what suits you.
Spain has some marvellous cities, each with it's own 'personality'. There are hundreds if not thousands of beaches, countryside as far as you can see, history, clubbing, activity centres, the list just goes on & on.
If you can give us an idea of what you would like to see, we'll give you our honest opinion of which parts are most likely to suit.
Remember, Europeans tend to travel by train or car rather than planes, so what may be considered a close city in the States may be a couple of days travel to get to in Europe.
But a quick snapshot would be Seville or Madrid for history, Barcelona for nightlife & culture, south coast for Party Nights & LOUD music, South west for Gibraltar & Africa, and the North for the mountains.
Sorry I cannot be of more help, but let us know what you like & we'll take it from there,
Alan & Katrina
Last Cruise: P&O Britannia March 2015
Next: Minerva April 2015
Then: Royal Princess August 2015
and : Queen Victoria January 2016
Golden, Grand(2), Caribbean, Sea(4+1 aborted)
Adonia(4+2), Arcadia, Artemis(2), Aurora(5), Azura(2), Britannia, Oceana(3), Oriana(11), Ventura(2), Victoria(5)
QM2(2), QE2(9), QV(6), QE, Caronia(2), Minerva II, Fred.Olsen(8), NCL Jade, =X= Eclipse, HAL Ryndam, Aza.Journey