Atlantida is a great place to stay. The only bad thing ( if you can say thats bad) is that it is quite sprawled out and there are loads of steps, so for the less mobile it might be a bit difficult to get aroud, however i do believe they have now put some ramps down.
There is loads to do for the kids during the day, the facilities are good, the cave bar and restaurant are good value for reasonable prices, but there are loads of eating places nearby ( its about 500 yards to sea front).
Allmen has answered your questions about loro park and the aqua park.
I am sure you will have a great holiday, wherever you go.