Hi, I am also going in october and stopping at the cye salou, last year it was quiet as places are starting to close for the end of season (i did go at the end of october though).
The cye itself is very nice and clean, looks old from the outside but the rooms are spacious and modern with flat screen tv's and microwave and hob facilities - you may want to hire a toaster and kettle from reception though (we take a travel kettle)
I was told that normally it is quite lively right until the end but due to finances people chose to close earlier last year, The weather is still hot (not scorching though and a bit cooler in the evenings) and it is possible to swim in the sea/pool but not for too long though as it gets cold.
Port Aventura is good too as it has the halloween theme on this time of year and the buses/trenet sevices are still fully operational including buses to the markets/nou camp/barcelona etc..
We tend to go in the summer for relaxing and taking in the sun and again in october for the excursions, port aventura etc.. as the queue's are shorter,
Hope this helps