I agree with much of what Bandit says. However, I lived in southern Spain too, although in Costa Almeria. Any holiday home owner worth his salt would not give false advertising e.g saying the holiday home is five minutes walk from the beach where the true situation is 15 minutes. People are too discerning nowadays to accept lies and ultimately will seek some form of compensation. Holiday Home owners need repeat business and this is achieved by telling the full truth always and keeping the rent charge at a reasonable rate.
Consider the following:- The nearest beach is one minute walk from the holiday home, but it is subject to currents and is dangerous. An apartment owner could truthfully say that the nearest beach is within 5 minutes walk, but not supply the danger possibility (hardly, telling the whole truth?).
Whenever I live in Spain, I enjoy meeting holiday makers on our apartment complex. I have no problem sharing a bottle of wine at lunchtime with anybody (You can buy wine from .50 cent per bottle). OK, save me from the loud apes who insist on singing "You'll never beat the Irish" at the top of their voices at 3.00am while getting sick into the swimming pool.
Now, back to Henry's dilemma. I would think that a privately booked apartment, car rental, low-cost airline flights would be the way to go. Furthermore, I think it is the cheapest option and has the most positives going for it. Privately booked accommodation is usually better than your normal package holiday. Washing machine, television, hairdryer, sunbeds, parasols, bar-b-que, patio furniture, books, DVD etc are provided and at no extra cost. Privately owned complexes are smaller and everybody enjoys the pool which seldom if ever would become overcrowded.
Kids Club:- If this is a must, then the package holiday is the way to go. Personally, I don't see much in favour of these Kiddies Clubs (but, I am willing to concede that I don't know much about them). But, most Spanish resorts provide free childrens play areas, in fact they put us to shame for what we have to offer generally in Ireland.
Mojacar Playa is an ideal family holiday location and if a package is required then Falcon Holidays serve it from Dublin, Cork and Shannon. If booking a package, I would suggest ringing the hotel/apartments in advance and seeking accommodation as far as possible distant from the loud pop bands. These places would have kiddies clubs, large swimming pools and huge play areas.