First, Disney is huge. If you wanted to experience each attraction only once, you would need multiple days per each park. Our very first trip we spent two weeks, and we weren't able to fit everything in we wanted to see. This was with us touring open to close, no afternoon breaks, and crowds were almost nonexistent, so our wait times were minimal. So, that kind of gives you an idea of how much there is to do.
Definitely, pick only one or two parks and stick to those. Switching parks wastes too much time, especially when you won't even begin to see half of what there is to see in a full day.
Based on your posts, AK seems like it would be a good fit. There is a Safari type ride where you ride in an open air truck through a savanna area to see African animals. Then, there are zoo like areas with animal enclosures. There is also a small petting zoo. There is in informative bird show. On top of that, there is a Dinosaur themed area with a playground, two kiddy Dinosaur rides, one more intense indoor dark dinosaur ride, and a dinosaur themed carnival area.
However, based on you saying the kids like hands on interactive things, the biggest draw at this park for your kids may be the Wildernesses Explorers game. Basically, there are about 30 kiosks set up around the park. Each kiosk has a different educational activity you can do to earn a Wilderness Explorer's badge, like in the movie UP. Some of the activities are relatively simple and quick, some are more complex and time consuming. You do not have to do all 30, but can pick and choose. This was a huge hit with the kids in our family, and one of their favorite parts of the trip.
There are other attractions at AK as well, but these the ones listed above will probably appeal to your kids ages and interests the most.
As far as a second day, take a look at what the other parks offer. Get a guide book from the library or visit Allears to get a better idea of which park might appeal to your family the most.
MK is the park with the castle. It is what most people think of when they think of Disney. The attractions are themed around different Disney movies such as Pirates of the Caribbean, Winnie the Pooh, Snow White, Monsters Inc., or Toy Story to name a few. The park consists of a mix of rides, shows, and parades.
The rides are not like anything you will have experienced at a carnival or at most other amusement parks. There are only 4 coasters total (1 kiddy, 2 mid range, and only 1 intense more stereotypical coaster, none go upside down, all except the last are pretty tame) There is one log flume ride that has a large drop at the end, and there are tea cups that spin, and one ride that spins high off the round. That is the extent of the MK thrill rides. Everything else, moves slowly along a fixed track or a waterway, and you pretty much just look at the sets as you pass them by. The point being, don't discount Disney rides because your kids might not be big fans of scary carnival or amusement park rides. Those are usually much more intense than Disney. For the most part, Disney wants grandma, mom, dad, and the baby, to all be able to ride together.
Also, at MK there are two different interactive scavenger hunt type games you can sign up to play for free, a pirate themed one and another called Sorcerer's of the MK. These may appeal to your kids as the player gets to interact with different game elements hidden in the parks.
Epcot is basically divided into two parts, 1) science and technology and 2) world cultures. The science side of the park has a small aquarium, many interactive exhibits, a space rocket launch simulator, and a number of other attractions based on educational themes. This was another huge hit with the kids for us due to all the hands on stuff in this park.
The world cultures section of the park was not as big of a hit, but ok. It is mainly made up shopping and restaurant areas, but there are a few interesting shows and demonstrations that take place in this area as well (we enjoy the Chinese acrobats). There are a couple of boat rides that were a big hit and also fun hands on kids stations for getting your passport stamped or a Duffy travel bear colored (not sure if they still do the bear). Casts members in these areas are also happy to interact with kids and teach them simple words or phrases in their language. This area can be fun if the child is interested in learning about another country, and you really take the time to explore.
HS is kind of hard to explain. It used to be a working production studio and was themed around the idea of movie making, what goes into making movies, the behind the scenes type stuff, that sort of thing, but most of that theming has been lost over the years. Now, it is a mishmash of Star Wars, Toy Story, a number of misc unrelated shows, and two thrill rides. If you will be coming back once the new improved Star Wars section opens, I'd save this park for then. If your husband wants to get his Star Wars fix in, maybe sign up to do the Void game in Disney Springs on a non park day. It is a Star Wars themed virtual reality game, and you wouldn't need a park ticket to play it.
Once you've decided on a park, choose a few attractions for a Must Do list. You won't be able to see all of any park in 1 day, so plan on seeing a few favorites, then go from there if you have extra time.
How much you will get through will greatly depend on your family's touring style, how fast you move, the crowd level, how many breaks you take, how much shopping, how many snacks and meals, how many character autographs. Some people only fit in 5 or 6 attractions in a day. On the other extreme, some people are able to do 20+ attractions in a day. I'd say somewhere around the 10 to 15 attractions a day range is more realistic for the average family, but even that is based on crowds, planning skills, and number of hours spent in the park.
