Whilst I couldn't imagine anything like spending such a high amount of time in those parks, I would suggest Hotel PortAventura to be your best option. Mainly as it's closer to Salou and, therefore, other life. I recommend taking a trip to the roman ruins in Tarragona, too - and possibly the train to Barcelona for a day.
Gold River and its complex is probably the nicest themed of all the resorts at PA, but it's in the middle of nowhere and you will feel isolated from the other hotels. If money is no object, though, Callaghan's at Gold River *are* the best rooms in terms of value vs. quality, and the breakfast in the Callaghan's is one of the strongest points about the whole resort.
I can't say I have a particularly strong impression of PA's general operation, the buffets were not great and the bars brightly lit with young children running round till an early hour. The saunas were closed and some of the bars were, too.
I have no idea what Salou is like - I stayed in Tarragona once as Salou looked like it was all irish pubs and chip shops.
Sorry to be less than positive