We loved Solecito, but it's a while since we stayed there - our kids were about 8 and 5 at the time. Solecito is smaller, and there was more going on at Mariners in terms of things for kids etc. However, our kids loved the pool at Solecito and we loved the place: small and friendly. 2 bed apartment had 2 balconies and one bathroom ensuite which was a bonus.

They are not far apart - you can see Mariners from Solecito - and I would stay in either again no problem, although have stayed in better locations in Alcudia in terms of things to do within close distance. I think if you want to have more to occupy the kids then Mariners would be the better choice - my kids made friends at Solecito on arrival so didn't bother us!