I have been fishing there for about ten years. It can be great any time of the year as long as you know where to look. In the summer outside points and deeper channels of the flats hold fish. Snook, Tarpon, Reds, permit, trout, can be had all year with certain times being better than others. The everglades and ten thousand island are a great place to fish and explore and there is always somthing to catch. Offshore is a different story, some grouper mostly shorts, cobia, macs, shark, permit, and others. No palegics, blue water just to far, better off running south to Key West 90mi due south. Just shoot me a pm and I will answer any specific questions, there are some great people down there that will help you allot in learning a few new spots.
I know you didn't ask for a charter, but just e-mail this guy, Capt. Keith, he's a close personal friend and one of those guys that loves to talk fishing. Just shoot him an e-mail about the Marco Island area, and he will fill you up with free info.
Freelance Captain, Currently on the "Sto Bene" or "Low Bidder" or "Indemnity" depending on the day
I run a Viking on a freelance basis that is based out of Ft. Myers. Fish that area about 1-2 months a year. Inshore is some of the best you will ever find. There is nothing like running around the Everglades and 10K where you may not see another boat the whole day. Try tripletail fishing, when in season it is tons of fun.
Offshore is pretty good for bottom fish and excellent for kingfish. Plenty of structure, natural and man made, that holds fish. Try the big wrecks in 150'-250' range for mako sharks and wahoo. Mako are not consistent but the wahoo fishing is pretty good. It would surprise you what lurks out there. As mentioned above, the pelagics are pretty far out. Id say, 130nm-140nm W or SW out from Marco to the 100 fathom break. You would be better off running down to the ocean side of the Tortugas. That place is a whole different world and holds tons of fish. Yellowfin and marlin are a possibility between the Tortugas and Key West at the right time of year.
It's going to be a whole different world than what you are used to in NJ. I hope you speak Spanish.
My wifes grand pappy lived down there, good bridge and pier fishin for the land based angler. Sheeps head, snook, snappers. Boat load of sharks they seemed to be everywhere. Look up a local tackle shop they should be able to give you some info. peace