My family is coming to spend our holidays in Playa Blanca on October. We are going to rent a car. If anybody has some good ideas where to go/see/visit by car, I would be happy to hear them. We have two kids with us (5 and 8 years). Any water park near to visit?

Theres a lot of stuff you could visit.
Water park in costa teguise(mixed reviews)
Rancho texas theme park, (good for the kids) in PDC
Fire mountian
The green caves
Mirador del rio
El golfo
Papagayo (are you allowed to take hire cars there?)
the north of the island in general for the views
Famara beach
The list goes on and on!!
If you have a look at the attractions / excursion pages on this site it will give you a good idea of what there is, but you can fill a week easily with trips out.

whatever you decide on im sure youll find plenty to do and therse no shortage of eating and drinking places on all of those routes.

Oh, and if you have kids of that age try Mcdonalds with a play area near matagorda