It is often easy to do your own thing and there is little danger of missing the ship if you are sensible
I suggest in Palma you simply take in the city-the cruise line usually puts a bus to take you to the centre (I walked it last time-too far in the heat!)Palma has a lovely cathedral etc and could take a full day
I vaguely remember Almeria as being somewhere else you can stroll around
Malaga is a lovely city and the ship docks close in-it has nice beaches etc-if you want to go further get the train to a resort (eg Benalmedena)
I have never arrived in Ibiza by ship but think they dock in Ibiza (Eivissa) town-once again this is a lovely city to look around yourself
Whatever you decide to do I hope you enjoy it-most first time cruisers rapidly become second/third/fourth etc cruisers!