In April and because you want some sunshine, less than 4 hours travelling and because there are at least three of you.
I would suggest Mojacar Playa (Costa Almeria) for the following reasons:-
1. Ryanair serves Almeria airport from Dublin and Murcia airport from Shannon.
2. Costa Almeria has the driest climate of mainland europe and the least rainfall.
3. The beach is within 5 minutes walk of most apartments
4. There are many walks on the level and as difficult as you want
5. There are several childrens free play areas of decent quality along the playa
6. The restaurants are magnificent and you can have dinner (3 course) from €9.00.
7. Drink is also inexpensive.
8. Mojacar Playa is a working town all year round and therefore has supermarkets like in Ireland within walking distance of nearly everywhere.
Hairdressers, boutiques etc are nearby also.
9. You can buy wine for as little as 20c per bottle (however, I recommend you spend €3.00 and you would get a bottle the quality of €26.00 in Ireland).
10. Although not guaranteed the temperature will be in excess of 23 degrees most days.
11. If you are renting a car (recommended @ €100 per week for a Ford Fiesta) there are many beautiful drives to Cabo de Gata National Park (5 miles distant) and Mini Hollywood where several classic films were made.
The coast provides numerous scenic routes also.
12. The journey time to Almeria from Ireland by plane is under 2.5 hours.
13. You can bring back whiskey at €10 per bottle and cigarettes (incl John PLayer Blue) at a fraction of the price here.
14. Rent a privately owned centrally located apartment @ €350 for the week.
And the Bad Points:-
1. The end of your holiday
2. Returning to rainswept Ireland