Obviously all national parks are best seen outside of your car, but most of the western parks are at least worthwhile to visit even if you're just passing through. These South Florida parks are completely different, they aren't really drivable (you physically can't drive to Dry Tortugas, can barely enter Biscayne by car and while there are plenty of roads through the Everglades you really don't see anything worthwhile).
Also unlike the western parks they aren't especially hikable. Everglades is the only one where it's really an option and I wasn't especially keen on taking three people I'd be responsible for keeping alive out into a gator and python infested river.
So unlike basically every other experience I've ever had with my Dad in an NP, we invested heavily in some professional tours. I already mentioned the ferry to Dry Tortugas. We also had a boat tour scheduled to some islands in Biscayne Bay. Unfortunately my daughter had a cough and they were extra COVID cautious so we didn't get to do that one. That left us essentially walking out on a jetty into Biscayne Bay from the VC. We saw a ton of iguanas (non native species) and plenty of fish. Encountered a number of dudes who could have passed for the darkness brothers and looked like they would have played for the U 20 years ago. @creepycoug. Wasn't a single @dflea or @YellowSnow cracka fishing out there, all brothas.
So Biscayne was kind of a bust as we only scratched the surface on it. Definitely a place I'd like to explore more.
Did get a shot of Pops and the kids I can actually share there.
Now to the easily the best part of the trip. Everglades National Park is huge, iconic, unique and yet not entirely what I expected. I've always associated the Everglades with gators and airboats, and there are plenty of both. But there's a ton more to it than that.

Everglades was actually the first NP set aside for environmental/ecosystem reasons rather than scenic ones. And most of it is not what I would call especially beautiful. It is absolutely full of animal life though, and a lot of animals you're not going to see anywhere else in the NP system. Certainly not anywhere out west.
As the third largest park in the lower 48, Everglades actually preserves 7 unique ecosystems, rather than just the obvious swamp I've always associated with it. We got to check out a number of them:
Tram tour through the poorly named Shark Valley (this is what most would think of when thinking of the Everglades). Saw a number of gators here, a black snake of some sort (much smaller than a python), a few turtles and a crapload of wading birds. Most exciting experience was at the one stop the tram makes there was a nest of baby gators we were able to view from a distance. I took the kids over there, we looked, and then we heard a low growling sound. I was curious as hell but smart enough to gtfo there. Told the tour guide about it and he said "yeah that was Mama letting you know you were too close to her babies."
My son swears the guide is wrong and it was a Florida Panther who was babysitting for the Mama Gator.
CSB

We also did the classic airboat tour. Lots more wading birds and gators, and saw a bunch of turtles on this as well (softshell and hardshell). I had done an airboat tour in November years ago and the wildlife was much more plentiful so it was a bit of a disappointment for me. Apparently the water levels are lower November to April and so you see a lot more critters then. Summer is the wet season and they have a lot more water to hide in. But the other three had never been on an airboat and were very impressed with what we saw.
But the highlight for all four of us was not these more classic Everglades experiences, it was what did on the Everglades coast. The glades includes large chunks of the south Florida coastline were the river of grass meets the sea. This brackish environment is absolute gold for wildlife. We did two tour boats out here - first on the southwest side through 10,000 islands and secondly at the far south edge at Flamingo. Both were extremely worthwhile.
The 10,000 Islands trip was easily the best though. We went out amongst the mangrove island (basically a floating tree that builds a root down below the water line and creates it's own island) in this extremely shallow brackish water and honestly my big hope was to see a manatee. We did see one although we didn't get a very good look. On that end it was a bust.
But we found a pod of bottlenose dolphins who decided to ride in our wake for a good 5-10 minutes and it was probably the most fun my kids have ever had. Hell up there with the most fun me and pops have had too. Pics don't do it justice but this site doesn't have a good mechanism for uploading video so it's the best you'll get.
Also saw tons of seabirds: Ospreys and kites and plenty of others.
My son had one big goal for the trip that hadn't been accomplished - he wanted to see a crocodile. So we added an extra trip and went to the aforementioned Flamingo for another boat tour with the express purpose of seeing some crocs. We did see four or five (none especially close). We also had a much closer encounter with a couple manatees this time around including a baby one.
Both kids completed some assignments and became Everglades Junior Park Rangers which they were very proud of. My son was most excited to have seen the crocodiles, my daughter fell in love with the manatees. The dolphins were far and away the highlight for me.
All told I think we spent about 2 1/2 days exploring the Everglades.
Worth all the tim and every pemmy.
If you ever get the chance to visit it's easily my favorite one to visit of any that I've seen east of the Rockies.