Why not take a trip to Barcelona? There's a cheap train service from Blanes (just up the road from Llloret de Mar); your rep should know the best way to get there.
In Barcelona you can buy day tickets for unlimited travel on the Metro, tram and bus services. (Again, the fares are cheap. The ticket is called a T-Dia). This will enable you to visit places such as the Zoo (nearest Metro stations Barceloneta or Ciutadella-Vila Olimpica), Aquarium (nearest Metro stations Barceloneta or Drassanes) and the Tibidabo funfair (FGC station Avda Tibidabo). See here for some further information:
http://www.bcninternet.com/Whatson/children.ht m
Barcelona is a great city for adults to explore with kids. Take a stroll along the famous and atmospheric La Rambla. It's a mile long and there's always plenty going on. The Metro stations are Placa de Catalunya and Catalunya (both at the northern end), Liceu (in the centre) and Drassanes (at the southern end).
When you get tired, remember that Barcelona has some great beaches and loads of good seafront places to eat.
Chris