Hello! Well, you are about to have a really fun time with your little one! Enjoy! In my opinion, the best Disney parks for kids that age are Magic Kingdom, and Animal kingdom. You may like what used to be called MGM studios and is now Hollywood studios I believe. Magic Kingdom is really the best of all 4 Disney parks for a 3 to 4 year old child though. Also, if your hubby is into racing at all, they have the Richard Petty speedway at that park, right outside. He can do a rid along or even take a day to learn to drive one of the race cars there on their track. It is something that my husband LOVED, and did several times. I guess for a guy speeding around a racetrack at 130 to 140 mph is a rush like no other, and I love the photos that we purchased as well as the many I took of him in his helmet while he was in the car. (our kids age 4 and 7 at the time) liked watching thier Dad race the car too. (both girls by the way) Ok, back to theme parks. I am not sure what the aquarium in your area has for shows, etc, but we actually have annual passes to Seaworld because we love it so much! They have several shows that your child as well as you and the hubby would enjoy. They change the shows quite often, and they also have rides, as well as places where you can go to feed the different animals. I would reccomend bringing a backpack with lots of water bottles and even snacks as the park itself is quite pricey on their food and drinks. (more than most) Also, there aren't as many choices for places to eat, so I would look online at the resteraunts in the park, and if nothing appeals to you, maybe pack some sandwiches for that particular day. Most of the other parks have a large variety of places to eat and they range in cost, but Seaworld is a little limited. The park however is way worth it. They even have a whole kid zone behind shamu stadium where it's like a carnival and water park in one for kids your child's age. There is a HUGE climbing structure with tunnels and nets, and you could really spend hours there alone if you wanted to.
Our very Favorite theme park in Orlando is Universal Studios. The "sister" park next door, Islands of adventure is awesome too, and is where most of the action hero stuff is. (as well as the new Harry Potter rides and attractions and dinosaur world) Universal is by far the best theme park in Orlando and your child will have the most fun there. There are rides, shows, and kids water parks all inside the park, and even little play areas. There is a Barney show, if your child is into Barney. Nickelodean Studios is there, and they have loads of very fun things to do and see. I wouldn't come to Orlando with my child and not go to Universal. You can get the 2 park passes that allow you to go from park to park. (Universal and Islands of adventure) It's the best value. They have concerts and shows there too, and usually they are included in your admission cost, unless they are in one of the places on citywalk. Then you have to pay an additional fee. We also have annual passes to these 2 parks, and I have to say, these are the ones that we go to most often. We have been going there since our oldest child was 7, (she is 21 now) and we have 4 kids. They all have a blast there, and so do we! We have stayed on site at the 3 different hotels, and also off site. On site allows you to get free speed passes for the rides, but you can also purchase these without staying at an onsite hotel. I think you are stayiing at one of the hotels there though? Well, in the summer the lines are no way near as long as the winter, so you may not even need the speed passes. It will be very hot, so make sure that you dress in light clothes, and I would pack some extra so you can get wet and change when you want to be dry again. We usually wear swimsuits under our shorts, and also just wear flip flops or sanadals so when your feet get wet they don't end up hurting. (they will if they can't dry) Also make sure you bring big ziplock bags for your camera and cell phones, etc to keep them dry on the water rides and in the water play areas. You will get wet! (you will want to since it will be hot) The nickelodean resort is a really fun place to stay all by itself, so I would make sure I kept a day (at least) open to just hang around the resort and use the pool and ammenities there. When our kids were that young, we would plan a day at a park, and then a day at the hotel with maybe a short outing to a local resteraunt or local tourist place close by and then relax, and then day 3 we would go to the next theme park. If you do every other day or at least give yourself a couple of "down" days at your resort, you will not get as easily tired out, and also your little one will really enjoy all of the trip including the resort where you are staying. Ok, one last tip...... try not to plan to stay at all of the parks from morning to night. Even though they all boast big nighttime light shows or fireworks, you will be really tired form your day. Your child will be wanting to go back to the fun resort to use the pool, etc. I would pick a couple places to plan on staying until the park closes, and then get there a little later in the morning. For example, Magic kingdom has a phenominal show at the end of the night, and it's well worth the wait to stay and see it. Seaworld and Universal really don't do much different at night than during the day, unless they have a concert on a particular night. Seaworld does have the shamu show at night, but honestly I prefer the daytime one anyway because you can see more of what is going on, and there aren't loud noises going on while you are trying to focus on the show. Well, I hope that helps. It's just one Mom's opinion and I have been going to these parks for YEARS. We actually moved to Fl. after several years of taking our annual vacation here and going to the parks, so I feel pretty knowledgeable when it comes to them. I hope that you all enjoy your trip!