spian?

You don't say what it is you are interested in, beaches, nightlife, culture ? .. What is it about staying in one of these particular Cities that you think you find appealing ? .. How long is your intended visit? .. Are you thinking Malaga or Alicante because of their airports ? If so, then perhaps consider some of lovely towns up the coast from these areas that have great Rail/tram connections, many of which I would personally prefer. ..
Do you plan on renting a car? ..

If it starts in March and goes into April, the best bet is to start south and work north. We went in April 2012, unfortunately it was an unusually cold April both north and south so we got very little nice weather. We drove through snow between Jaen and Granada in mid-April. If you want beach weather in the south and can stand some cold weather up north, you could start north and give yourself a little better chance for very nice weather once you get south. Most people think of Spain as a very warm destination. That's true in summer. In winter however, especially in the north and at elevation, it can get really cold, including freezing weather, windy, and snowy in the winter.