Actually, talking of Ryannair, I had an amazing summer break in Seville that was really really cheap. We booked the hotel as well as the flight through them and the hotel was amazing!!!!! I loved Seville but is was boiling (when I was there it was the hottest place in Europe, approx. 42 - 45 celsius). Buses have air conditioning, you get to take afternoon naps, and they have great markets and ice cream parlours. The food is great too - tapas! My spanish is borderline useless but I survived there OK.
The only bad thing though was that a couldn't find anywhere near my hotel that sold coca-cola during siesta time, or ice cream for that matter, so you really do have to go back to your hotel.
It was great fun in summer, but I guess it's probably really nice in spring time too. So anyway, Ryanair = amazing! And their planes aren't a disgusting icky orange!