We use a trolling line with a diving spoon in deeper water and in shallower water a spinner. Flashy and green/yellow trailers works best... but we are no experts. The problem we have is that the big fish like big lures so rigging them up requires a hire test and steel leaders which are really bad for the smaller fish.
You can spend a gazillion dollars on this stuff!!! Penn makes pretty good stuff, but I really prefer Shimano over them. For a spinning rod (open), I think Daiwa is my preference.
So to do it right, yo uhave to have several different rods and a lot of different lures. But to save money, just get one troller (will end up being the most expensive too), then a cheaper spinning (open face). For the docks and kids, just get a cheapie from Walmart.
Now if you really want to catch fish all day long for fun, use rib meat. Catfish love that stuff and it is hard for them to pull it off the hook. But since saltwater catfish are nigh near unedible, it is just for fun. Snapper will hit almost anything and love the docks - but the bigger snapper like to be closer to wrecks or pilings or stuff further offshore.
SO now that it sounds like I know what I am talking about, here is the biggest fish I have caught this year:
That is a really tasty great barracuda (don't eat them... dangerous). SO I am no expert. In fact, my little boy told me last weekend that, "Catching a fish in a sailboat while trolling is very rare, right daddy?"