There's lots to do in Puerto Banus, you'll find no shortage of bars and restaurants fitting budgets of all sizes. There's amusements and trampolines for the kids, as well as a market area. There are loads of shops and a large department store called El Corte Ingles which contains within an enormous supermarket called Hypercor.
Most holidaymakers take a trip down to PB just to do a spot of people-watching on the promenade where you'll no doubt see some incredible sights including some of the most expensive yachts and cars on the planet.
For parking, you can get lucky and find a spot on the road for free, or you can park in the huge underground car park (not so free!)