Ticketing for the Alhambra
One tip. The main ticket office and entrance is at the far end (from the city centre) at the top of the hill and close to the public car parks. It's up at the top so folks can drive around Granada and enter the car parks without the need to navigate any city streets or wind up in a car free area !
If you are staying in the city centre in the vicinity of the Cathedral area or Plaza Nueva you would not need to get up to the main ticket entrance IF you wanted to collect your entry tickets at the Alhambra from the official shop at Calle Reyes Católicos nº 40.
According to http://www.alhambra-patronato.es
"Here, one can also purchase and collect admission tickets to the site paying by credit card. Official maps and leaflets of the different programmes and activities to take place at the site are furthermore available."
This is quite useful because it makes a good alternative if you like to walk up along Cuesta de Gomerez to the Alhambra through the Puerta las Granadas (built by the Christians and into the park area and enter via the Justice Gate which was the original Moorish main entrance into Calat Alhambra (the Red Fortress) :
http://en.wikipedia.org/wiki/File:Alhambra_Gatehouse.jpg
having said that, if you can pre order your entry tickets and collect them at the lower shop (Tienda de la Alhambra) you can then choose the 30 minutes entry time for the main 'attraction' which is the Nasrid palaces. The daytime tickets that you can buy are for 'sessions' being morning and afternoon and within these two 'sessions' you can select your ideal entry 'slot' for entering the Nasrid Palaces gate. So you need to be at the Nasrid gate in good time otherwise if you miss that 'slot' you will have to start all over.
http://www.servicaixa.com/nav/landings/en/mucho_mas/alhambra/alhambra.html
Now pre ordering the ticket and paying the extra €1 does at least allow you to plan your visit with some foresight and choose the best time for beginning your tour of the palaces. You will need about 2 hours minimum in my opinion to look round the palaces. Some people prefer to take the early slot before any post breakfast or groups congestion but it all depends on how many visitors arrive on that particular day.


Capitulation of Granada by Ortiz, Capilla Real.
A beautiful ceiling in Lions' Court.
The Comares Palace
Route through El Vacar