hi, we've been in this area five times now and I would go again and again.
few tips;
buses run to barc for round 17 euros, very easy and alot cheaper to do, instead of the tours theres plenty of bus stops and buses or harder way to do it is the train going from salou (but it is hard the first time till you know your bearings I would stick to the buses).
waterpark and themepark, go on the change over day normally tuesday, you will find it so easy to get on rides and such like.
any shopping take the bus into salou same things at lower prices.
oct weather is alot hotter than here!!!! you may get break though rain where it pours down solid but in the morning its clears up or it did when we were there. buy those little plastic macs that roll up to nothing.
the only tour run worth doing to barc, is the foutains at night. if you go in the day watch out for the cons and pick pockets! doing barc on the bus its hard to get to these places on your own. once in barc head to the bottom of la rams (as early as you can) there are tour buses parked by the harbour, they work out expensive but still works out cheaper than a tour bus from salou, well worth it as they take you all over the city,after that stroll down la rams at your own pace you will have seen everything. you cant do this with a tour bus as there isnt that much time. oh and go to the marine center on the harbour its brill.
never pay the first price you see further down the road it will be cheaper.
hope something I listed gives you help